Soundproofing material manufacturing method using leather scraps

Abstract

Disclosed is a soundproofing material manufacturing method using leather scraps, which uses leather scraps, and thus reduces costs, is eco-friendly and provides an excellent soundproofing effect. The disclosed soundproofing material manufacturing method using leather scraps comprises: a first step of pretreating leather scraps; a second step of cutting and pulverizing the leather scraps so as to produce a pulverized product; a third step of drying the pulverized product; a fourth step of mixing the pulverized product with an aqueous adhesive, latex and water so as to produce a mixture; a fifth step of compressing the mixture so as to produce a molded product; and a sixth step of drying the molded product.

Description

Method for manufacturing soundproofing material using cowhide

[0001] The present invention relates to a method for manufacturing soundproofing material using cowhide, and more particularly, to a method for manufacturing soundproofing material using cowhide that realizes resource circulation by recycling various cowhide (waste leather, remaining leather, etc.) obtained from products such as automobile seats.

[0002] In response to the recent increase in violent incidents caused by noise conflicts between floors in apartments and other multi-family housing, the Ministry of Land, Infrastructure and Transport announced a "Measures to Address Inter-Floor Noise" in December 2023, refusing construction approvals if noise standards are not met. Consequently, demand for soundproofing materials is expected to surge in apartments, villas, and other multi-family housing, as well as in new school construction.

[0003] Conventional soundproofing materials are manufactured by heating and pressurizing the top or bottom plate, or by applying heat to a mold using boiler equipment before inserting the material. These processes are complex, energy-inefficient, and require significant capital investment. Furthermore, sponge, Styrofoam, rock wool, and glass wool are commonly used as soundproofing materials. These materials, however, emit toxic gases in the event of a fire, and rock wool and glass wool are known to be harmful to humans, potentially causing lung cancer.

[0004] Accordingly, the development of cost-effective car seat scrap leather and soundproofing materials using eco-friendly, natural scrap cowhide is gaining traction. The annual volume of leather scrap leather, including scrap leather and scrap leather from car seats, amounts to approximately 4 million tons, most of which is disposed of entirely through landfill or incineration.

[0005] This method of disposal causes environmental pollution and soil contamination due to increased greenhouse gases from carbon emissions, but there is currently a lack of technology to utilize the leather or waste leather from car seats.

[0006] To solve the above problems, it is necessary to not only prevent soil and environmental pollution by recycling automobile upholstery or waste leather to realize resource circulation, but also to develop technology to manufacture soundproofing materials with excellent soundproofing performance.

[0007] The present invention was created in consideration of the above-mentioned points, and its purpose is to prevent environmental pollution and soil contamination by realizing resource recycling through the use of cowhide, and to provide a method for manufacturing soundproofing material using cowhide with excellent soundproofing performance.

[0008] In order to achieve the above object, the method for manufacturing a soundproofing material using cowhide according to the present invention comprises: a first step of pretreating cowhide; a second step of cutting and crushing the cowhide to produce a crushed product; a third step of drying the crushed product; a fourth step of mixing a water-based adhesive, latex, and water with the dried crushed product to produce a mixture; a fifth step of compressing the mixture to produce a molded product; and a sixth step of drying the molded product.

[0009] In the second step, the leather can be cut using a cutter and then crushed using a crusher to a size of 2 to 5 mm.

[0010] The third step above can be carried out by drying the pulverized material at 45 to 50°C for 60 to 72 hours and then naturally drying it.

[0011] In the fourth step, the mixture may include the pulverized material, water-based adhesive, latex, and water in a weight ratio of 1:0.2 to 0.4:0.05 to 0.15:0.005 to 0.015. Here, the water-based adhesive may include a water-based bond, and the latex may include natural rubber latex.

[0012] The fifth step may be to produce a molded article by placing the dried pulverized material into a mold and press-molding it at a pressure of 60 to 100 tons. Here, the molded article may be in the form of a pad, and the thickness of the pad may be 2 to 2.5 cm.

[0013] The above sixth step can sequentially perform cold air drying, hot air drying, and natural drying on the above molded product.

[0014] The method for manufacturing soundproofing material using cowhide according to the present invention reduces the costs associated with incineration and production by utilizing cowhide, and by promoting resource recycling, it reduces soil and environmental pollution. Furthermore, as an eco-friendly material, it is harmless to the human body while providing excellent heat, dust, and soundproofing properties.

[0015] Figure 1 is a flowchart showing a process for manufacturing soundproofing material using leather according to an embodiment of the present invention.

[0016] Figures 2 and 3 are photographs showing the cut leather and the crushed leather crushed by the crushed material production process of Figure 1, respectively.

[0017] Figure 4 is a photograph showing the mixture creation process of mixing water-based adhesive, latex, and water into the pulverized material of Figure 3.

[0018] FIG. 5 is a photograph showing a pad-shaped soundproofing material manufactured by a soundproofing material manufacturing process using leather according to an embodiment of the present invention.

[0019] FIG. 6 is a photograph showing an example of a pad-shaped soundproofing material manufactured by a soundproofing material manufacturing process using leather according to an embodiment of the present invention being installed on the ceiling of an apartment, etc.

[0020] All terms described in this specification are currently widely used general terms selected in consideration of the functions of the present invention, but these may vary depending on the intention of a person skilled in the art, custom, or the emergence of new technologies. In addition, if the inventor specifies any term in the present invention, the meaning thereof will be described in the description of the invention. Therefore, the terms used in the present invention should be interpreted based on the actual meaning of the term and the overall contents described in the description of the present invention, rather than simply the name of the term.

[0021] Hereinafter, a method for manufacturing a soundproofing material using a leather according to an embodiment of the present invention will be described in detail with reference to the attached drawings.

[0022] Figure 1 is a flowchart showing a process for manufacturing soundproofing material using leather according to an embodiment of the present invention.

[0023] Referring to FIG. 1, a method for manufacturing a soundproofing material using cowhide according to an embodiment of the present invention includes a first step of pretreating cowhide; a second step of cutting and crushing the cowhide to produce a crushed product; a third step of drying the crushed product; a fourth step of mixing a water-based adhesive, latex, and water with the dried crushed product to produce a mixture; a fifth step of compressing the mixture to produce a molded product; and a sixth step of drying the molded product.

[0024]

[0025] [1] Step 1 (Pretreatment of the leather)

[0026] The first step is to preprocess the calf leather. The calf leather refers to scrap leather or residual leather left over after cutting when manufacturing leather products such as car seats. The car seat may be manufactured from natural leather or artificial leather. The natural leather is manufactured by extracting from calves, lambs, kid goats, etc., while the artificial leather may be composed of at least one of plastic resins such as PU, PVC, EVA, PET, etc. In the present invention, the calf leather of the car seat may be preferably selected and manufactured by extracting from calves. In addition, the calf leather may include waste car seat sheets manufactured by extracting from calves, etc.

[0027] The above pretreatment step may be performed by collecting, washing, and drying. Specifically, the pretreatment step may involve collecting the leather, cleaning it using a powerful multi-purpose detergent, and wiping off contaminants with a tissue or cloth, or cleaning it using a cleaning mixture. The leather, from which contaminants have been removed, may be naturally dried at room temperature (21 to 30°C).

[0028] The cleaning mixture may include water, shell powder, and baking soda. For example, the cleaning mixture may be mixed with shell powder and baking soda in a volume ratio of 0.05 to 0.25: 0.03 to 0.05 for every 100 parts by volume of water.

[0029] Shell powder may be included in a washing mixture. The shell powder may be manufactured through the following five-step process. That is, the process may include: (1) preparing and washing shells; (2) drying the washed shells in natural sunlight for 24 to 72 hours; (3) pulverizing the dried shells into particles having an average particle diameter of 2 to 5 mm using a roll mill; (4) calcining the pulverized shells by low-temperature firing at 400 to 500°C for 10 to 20 hours and then high-temperature firing at 70 to 1000°C for 5 to 10 hours; and (5) pulverizing the calcined shells into a fine powder for the second time.

[0030] The above shells may be at least one selected from clam shells, cockle shells, razor clam shells, scallop shells, and oyster shells, but are not limited thereto. The clam shells have various patterns such as stripes and waves and are composed of 89 to 99% calcium carbonate, 1 to 2% calcium phosphate, and others. The cockle shells are generally oval and are composed of 89 to 99% calcium carbonate, 1 to 2% calcium phosphate, and others. The clam shells have a shape close to circular and are composed of 89 to 99% calcium carbonate, 1 to 2% calcium phosphate, and others. The scallop shells have various colors, are fan-shaped, and are composed of 89 to 99% calcium carbonate, 1 to 2% calcium phosphate, and others. The oyster shells are composed almost entirely of calcium carbonate, and also contain gypsum and others.

[0031] Step (1) of preparing and washing the above shells is a step to remove impurities or contaminants in the shells, and it may be desirable to wash them using fresh water.

[0032] The above drying step (2) is intended to remove salt and odor remaining in the washed shells, and the washed shells can be dried for 24 to 27 hours, but is not limited thereto.

[0033] The above first crushing step (3) can crush the shells to an average particle diameter of 2 to 5 mm using a roll mill. If the average particle diameter of the shells is crushed to less than 2 mm, there is a risk that the shells will be crushed too finely and may scatter, and if the particle diameter is crushed to more than 5 mm, the firing described below may not occur properly.

[0034] The above firing step (4) can be performed by performing low-temperature firing at 400 to 500°C for 10 to 20 hours in an air- or oxygen-free state, followed by high-temperature firing at 700 to 1000°C for 5 to 10 hours in air. Therefore, if the firing temperature and time are below the range, impurities may remain, and the firing reaction may not occur properly, making it difficult to increase the calcium carbonate content. In addition, if the firing temperature and time exceed the range, the problem of the shell desiccation may occur. This two-step firing can enhance the antifungal and antibacterial effects as the calcium carbonate content increases. Ultimately, the leather washed with the mixture can be protected from mold, fungi, etc.

[0035] The above secondary crushing step (5) can be manufactured with shell powder having an average particle diameter of 1 to 5 μm. If the average particle diameter of the secondary crushed shell powder is less than 1 μm, it may be difficult for the cleaning mixture to be effective, and if it exceeds 5 μm, it may not be properly mixed with other ingredients.

[0036] Therefore, the above-mentioned shell powder can be mixed in a volume ratio of 0.05 to 0.25 per 100 volume ratio of the cleaning mixture water. If the volume ratio of the shell powder is less than 0.05, it may be difficult to improve the antifungal and antibacterial effects of the soundproofing material, and if it exceeds 0.25, it may cause a relative decrease in the content of other components, which may prevent the cleaning effect from being properly achieved.

[0037] The baking soda mentioned above can be included in a cleaning mixture. Baking soda is an environmentally friendly material with excellent cleaning properties and mildly alkaline properties. The mild alkaline properties of baking soda can neutralize fatty acid-based contaminants and grease, transforming them into water-soluble substances. Therefore, when baking soda and water are used, contaminants and grease can be thoroughly removed without using detergents that cause environmental pollution. Furthermore, the baking soda may be in powder, granular, or liquid form.

[0038] The above baking soda may be included in the cleaning mixture in a volume ratio of 0.03 to 0.05 per 100 volumes of the water. If the volume ratio of the baking soda is less than 0.03, the cleaning effect may not be achieved and contaminants may remain on the leather. If it exceeds 0.05, it may be technically meaningless.

[0039] Therefore, the pretreated leather can be helpful in manufacturing high-quality soundproofing material with anti-fungal effect by removing impurities.

[0040]

[0041] [2] Stage 2 (Creation of crushed material)

[0042] Figures 2 and 3 are photographs showing the cut leather and the crushed leather crushed by the crushed material production process of Figure 1, respectively.

[0043] Referring to FIGS. 2 and 3, the second step is a step of cutting and crushing the above-mentioned leather to produce a crushed material. Specifically, referring to FIG. 2, the above-mentioned leather is classified by size and grouped, and then the leather within the same group can be cut into pieces having a thickness of 2 cm or less and a length of 20 to 30 cm using a cutter. The cutter is a device for cutting the leather and can be any commonly known device. Next, referring to FIG. 3, the cut above-mentioned leather can be crushed using a crusher so that the size of the crushed material is 2 to 5 mm (all in width, length, and height). The crusher may be a leather cutting machine, but is not limited thereto.

[0044] Here, if the size of the above-mentioned pulverized material is less than 2.0 mm, the pore structure capable of absorbing airborne sound may be reduced, resulting in a deterioration in sound absorption performance for high-frequency noise. Furthermore, if the size of the above-mentioned pulverized material exceeds 5 mm, not only will the density of the soundproofing material be reduced, but the non-uniform structure may also result in a deterioration in mechanical strength and durability, and if the mixing is not performed properly, the pores between large particles may become too large, resulting in a deterioration in sound absorption performance for low-frequency noise.

[0045]

[0046] [3] Step 3 (Drying of crushed material)

[0047] The third step is to dry the pulverized material to manufacture soundproofing material. The drying step is to remove moisture, contaminants, dust, residues, etc. remaining in the pulverized material. Specifically, the pulverized material may be placed in a drying oven and dried at 45 to 50°C for 60 to 72 hours, followed by natural drying. In the present invention, natural drying may be performed at a room temperature of 21 to 30°C. The drying oven may use a conventional, known device. In another embodiment, if equipment capable of mass production is provided, the step of placing the pulverized material in a drying oven and drying it with hot air may be omitted, and only natural drying may be performed. The natural drying prevents warping compared to hot air drying, thereby improving quality, and can reduce costs for equipment and operation due to hot air drying.

[0048] Therefore, if the drying temperature is below 45℃, the drying time will be long, which is not only inefficient in terms of energy, but also moisture may remain due to non-drying, and if it exceeds 50℃, the pulverized product may burn or warp. In addition, if the drying time is less than 60 hours, moisture may remain due to non-drying, and if it exceeds 72 hours, the production time will be long, which may be inefficient in terms of energy, and may cause problems in mass production.

[0049]

[0050] [4] Step 4 (mixture creation)

[0051] Figure 4 is a photograph showing the mixture creation process of mixing water-based adhesive, latex, and water into the pulverized material of Figure 3.

[0052] Referring to Figure 4, the fourth step of creating a mixture is a process of bonding the pulverized material. The mixture can be created by mixing the pulverized material with a water-based adhesive, latex, and water. The mixture can contain the pulverized material, the water-based adhesive, the latex, and the water in a weight ratio of 1:0.2-0.4:0.05-0.15:0.005-0.015.

[0053] The above water-based adhesive is for bonding the pulverized material, and a water-based bond can be used. This water-based bond can be made of an eco-friendly material. Since this eco-friendly water-based bond does not use organic solvents, it is eco-friendly because it emits less volatile organic compounds, and it dries quickly, which can shorten the working time. In addition, it can be economical because it is cheaper than other organic solvent-based adhesives. Here, the water-based bond can be included in an amount of 20 to 40 parts by weight per 100 parts by weight of the pulverized material. If the content of the water-based bond is less than 20 parts by weight, it may be difficult to bond the pulverized material, which may reduce the soundproofing effect. In addition, if the content of the water-based bond exceeds 40 parts by weight, the content of the pulverized material is relatively reduced, which may reduce the strength, durability, and soundproofing of the soundproofing material.

[0054] The aforementioned latex is an environmentally friendly material, and natural rubber latex can be used to bond crushed materials and improve soundproofing. This natural rubber latex is not only environmentally friendly, but also durable, with excellent adhesive properties and soundproofing.

[0055] The above natural rubber latex may be included in an amount of 5 to 15 parts by weight per 100 parts by weight of the crushed material. If the amount of natural rubber latex is less than 5 parts by weight, adhesion and soundproofing may be difficult to achieve. Furthermore, if the amount of natural rubber latex exceeds 15 parts by weight, the cost increases due to the high cost, and the soundproofing material may become too flexible, making it difficult to shape into a desired shape. In addition, while elasticity may increase, sound absorption may decrease.

[0056] The water may be included in the mixture to facilitate bonding between the individual components. The water content may be 0.5 to 1.5 parts by weight per 100 parts by weight of the pulverized material. If the water content is less than 0.5 parts by weight, the mixture may be difficult to bind and thus difficult to mold. Furthermore, if the water content exceeds 1.5 parts by weight, the sound-absorbing function may be reduced.

[0057]

[0058] [5] Step 5 (Production of molded products)

[0059] Step 5 involves compressing the mixture to create a molded product. This molding step is intended to mold the soundproofing material into various shapes and specifications suitable for buildings such as apartments, multi-family homes, townhouses, and schools.

[0060] The molding method for manufacturing the above-mentioned molded article may be selected from sheet molding, extrusion molding, injection molding, press molding, etc. In the present invention, press molding is preferably selected. The press molding is a method of manufacturing a molded article by filling a mold with powder and applying pressure. Depending on the method of applying pressure, there are uniaxial pressing molding for one direction, and isostatic pressing molding for multiple axes. The molding method according to an embodiment of the present invention is mainly uniaxial pressing molding, in which powder is charged into a mold. Then, the mold loaded with powder can be pressed at a predetermined pressure to perform molding.

[0061] For example, a molded article can be manufactured by press molding, which involves pouring a mixture into a mold and manufacturing it at room temperature (21-30℃) under a pressure of 60-100 tons. If the pressure used to manufacture the molded article is less than 60 tons, the density of the molded article may be uneven, which may result in the generation of voids and weakened adhesive strength, which may deteriorate physical properties such as strength and sound absorption performance. On the other hand, if the pressure exceeds 100 tons, the density may increase excessively, which may deteriorate sound absorption performance, and since uniform molding may become difficult, fine cracks or other defects may occur, which may deteriorate the durability of the manufactured soundproofing material.

[0062] The shape of the above-mentioned molded article may be a pad shape having various shapes such as circular or square. If the above-mentioned molded article is a pad shape, the thickness of the pad may be 2 to 2.5 cm. Here, if the thickness of the pad is less than 2 cm, the physical properties such as sound absorption performance and durability may be reduced. Furthermore, if the thickness of the pad exceeds 2.5 cm, it does not significantly contribute to improving the sound absorption performance, and may actually increase the cost and weight.

[0063]

[0064] [6] Step 6 (Drying the molded product to manufacture soundproofing material)

[0065] The sixth step of drying the molded product is to sequentially dry the molded product through cold air drying, hot air drying, and natural drying to manufacture soundproofing material.

[0066] Cold air drying is a method of drying molded articles using low-temperature air without damaging them. The cold air can absorb moisture from the surface of the molded article. Hot air drying is a method of drying cold-air-dried molded articles using air at a temperature of 100-150°C, enabling uniform and continuous drying for mass production. Natural drying can dry hot-air-dried molded articles at 25-30°C. As another example, molded articles can be dried solely through natural drying.

[0067] Fig. 5 is a photograph showing a pad-shaped soundproofing material manufactured by a soundproofing material manufacturing process using cowhide according to an embodiment of the present invention, and Fig. 6 is a photograph showing an example of the soundproofing material of Fig. 5 being installed on the ceiling of an apartment, etc. Referring to Figs. 5 and 6, the soundproofing material manufacturing method according to the present invention utilizes cowhide, thereby realizing resource circulation and preventing soil pollution and environmental pollution, and is made only of eco-friendly materials (cowhide including cowhide), and has a simple manufacturing process, so that not only is the cost reduced, but also has excellent heat dissipation, dustproofing, sound absorption, and sound insulation performance, so that it can be installed in various places requiring soundproofing facilities, such as schools, apartments, and music rooms.

[0068]

[0069] Hereinafter, manufacturing examples, examples and comparative examples will be described in detail.

[0070] <Manufacturing Example>

[0071] [Experimental-Manufacturing Example 1] Shell Powder

[0072] 1 kg of oyster shells were prepared, washed with fresh water, and then dried in natural sunlight for 36 hours. The dried oyster shells were first crushed using a roll mill to an average particle diameter of 3 mm. Subsequently, the first crushed oyster shells were low-temperature calcined at 450°C for 10 hours and then high-temperature calcined at 900°C for 7 hours. The calcined oyster shells were then crushed a second time to produce shell powder with an average particle diameter of 2 μm.

[0073] [Experimental Manufacturing Example 2] Cleaning Mixture (including shell powder)

[0074] To prepare a cleaning mixture, water, shell powder prepared according to Manufacturing Example 1, and baking soda were weighed in a volume ratio of 100:0.15:0.05 and then mixed to prepare a cleaning mixture.

[0075] [Comparison-Manufacturing Example 3] Cleaning Mixture (without Shell Powder)

[0076] To prepare a cleaning mixture, water and baking soda were weighed in a volume ratio of 100:0.05 and then mixed to prepare a cleaning mixture.

[0077]

[0078] <Examples and Comparative Examples>

[0079] [Example 1]

[0080] The collected calf leather was washed with a cleaning mixture prepared according to Manufacturing Example 2 to remove contaminants, and then naturally dried at room temperature. The calf leather was cut into pieces 1.5 cm thick and 30 cm long using a cutter. The cut calf leather was ground into pieces 3.5 mm in size using a grinder. The ground pieces were dried at 45°C for 66 hours. 500 g of the dried ground pieces were mixed with 150 g of water-based bond, 55 g of natural rubber latex, and 5 g of water to produce a mixture. The mixture was poured into a mold and press-molded at a pressure of 80 tons to produce a molded article in the shape of a pad with a thickness of 2 cm. The molded article was dried with cold air, hot air, and naturally dried using a dryer to produce an experimental soundproofing material.

[0081] [Comparative Example 1]

[0082] Comparative Example 1 produced a soundproofing material in the same manner as Example 1, except that the cleaning mixture produced according to Comparative Manufacturing Example 3 was used.

[0083] Table 1 below shows examples and comparative examples according to the presence or absence of shell powder.

[0084]

[0085] [Example 2]

[0086] The collected leather was washed by wiping off contaminants with a cloth using a powerful multipurpose detergent, nb-1, and then naturally dried at room temperature. The leather was cut into pieces with a thickness of 1.5 cm and a length of 30 cm using a cutter. The cut leather was ground into pieces with a size of 2 mm using a grinder. The ground piece was dried at 45°C for 66 hours. A mixture was produced by mixing 500 g of the dried ground piece with 150 g of water-based bond, 55 g of natural rubber latex, and 5 g of water. The mixture was put into a mold and press-molded at a pressure of 80 tons to produce a molded article in the shape of a pad with a thickness of 10 mm. The molded article was dried with cold air, hot air, and naturally dried using a dryer to produce the soundproofing material of the present invention.

[0087] [Example 3 and Comparative Examples 2 and 3]

[0088] Example 3 produced the soundproofing material of the present invention in the same manner as Example 2, except that the size of the pulverized material was 5 mm.

[0089] Comparative Example 2 produced a soundproofing material in the same manner as Example 2, except that the size of the pulverized material was 1 mm, and Comparative Example 3 produced a soundproofing material in the same manner as Example 2, except that the size of the pulverized material was 10 mm. Table 2 below shows examples and comparative examples in which the size of the pulverized material, the content of the mixture components, the molding pressure, and the thickness of the molded material were different.

[0090] [Examples 4 to 8 and Comparative Examples 4 to 12]

[0091] Example 4 produced a soundproofing material of the present invention in the same manner as Example 2, except that the size of the pulverized material was 3.5 mm and the weight of the water-based bond was 100 g, and Example 5 produced a soundproofing material of the present invention in the same manner as Example 2, except that the size of the pulverized material was 3.5 mm and the weight of the water-based bond was 200 g.

[0092] Example 6 produced the soundproofing material of the present invention in the same manner as Example 2, except that the size of the pulverized material was 3.5 mm and the natural rubber latex was 25 g, and Example 7 produced the soundproofing material of the present invention in the same manner as Example 2, except that the size of the pulverized material was 3.5 mm and the natural rubber latex was 75 g.

[0093] Example 8 produced the soundproofing material of the present invention in the same manner as Example 2, except that the size of the crushed material was 3.5 mm and the pad thickness was 2.5 cm.

[0094] Comparative Example 4 produced a soundproofing material in the same manner as Example 2, except that the size of the pulverized material was 3.5 mm and the water-based bond was 50 g, and Comparative Example 5 produced a soundproofing material in the same manner as Example 2, except that the size of the pulverized material was 3.5 mm and the water-based bond was 250 g.

[0095] Comparative Example 6 produced a soundproofing material in the same manner as Example 2, except that the size of the crushed material was 3.5 mm and the natural rubber latex was 15 g; Comparative Example 7 produced a soundproofing material in the same manner as Example 2, except that the size of the crushed material was 3.5 mm and the natural rubber latex was 85 g; and Comparative Example 8 produced a soundproofing material in the same manner as Example 2, except that the size of the crushed material was 3.5 mm and the natural rubber latex was 50 g.

[0096] Comparative Example 9 produced a soundproofing material in the same manner as Example 2, except that the pressure during press forming was 50 tons, and Comparative Example 10 produced a soundproofing material in the same manner as Example 2, except that the pressure during press forming was 110 tons.

[0097] Comparative Example 11 manufactured a pad-shaped molded product having a crushed material size of 3.5 mm and a thickness of 1 cm, and Comparative Example 12 manufactured a soundproofing material in the same manner as Example 2, except that the crushed material size was 3.5 mm and a pad-shaped molded product having a thickness of 3.5 cm was manufactured.

[0098] Table 2 below shows examples and comparative examples in which the size of the crushed material, the content of the mixture components, the molding pressure, and the thickness of the molded material are different.

[0099]

[0100]

[0101] <Example of an exam>

[0102] [Test Example 1] - Antifungal test on washed cowhide

[0103] Test method: A specimen suitable for KS J 3201 was prepared, and the first step of Example 1 and Comparative Example 1, the pretreatment step (collection -> washing -> drying), was performed, and then an antifungal test using five types of mold strains was conducted. Table 3 shows the antifungal results according to the Examples and Comparative Examples of the present invention.

[0104]

[0105] Test Results: Referring to Table 3, Example 1 confirmed that no mold strains grew at all. On the other hand, Comparative Example 1, which did not contain shell powder, showed mold growth. Therefore, it was confirmed that the presence or absence of shell powder in the cleaning mixture affected the antifungal effect.

[0106] [Test Example 2] - Soundproofing (sound absorption)

[0107] Test Method: Samples of soundproofing materials according to the examples and comparative examples of the present invention were prepared, and their soundproofing properties were measured using a soundproofing measuring device. The soundproofing measuring device is a device that shows the transmission loss (transmission) in decibels through the amount of energy reduction incident from a noise source, and the measurement frequency is up to 6.3 kHz. Measurements were performed five times for each sample, and the average values ​​were taken. Table 4 shows the soundproofing effect results according to the examples and comparative examples of the present invention.

[0108] Test results: Referring to Table 4, all examples except Comparative Example 1, which had differences in the method of washing the leather for collection, and Comparative Example 12, which had differences in the pad thickness, showed excellent soundproofing effects, with noise reduced by up to 12 dB compared to all Comparative Examples.

[0109] Specifically, when comparing Example 1 and Comparative Example 1, which only differed in the method of washing the leather for collection, it was found that there was almost no difference in the soundproofing effect.

[0110] In addition, when comparing Examples 1 to 3 and Comparative Examples 2 and 3 according to the size of the pulverized material, it was found that the soundproofing effect was excellent as the transmission loss according to the frequency was 30 dB or more when the size of the pulverized material was within the range of the present invention. On the other hand, Comparative Example 2, in which the size of the pulverized material was 1 mm, showed that the transmission loss decreased at high frequencies as the frequency increased, and Comparative Example 3, in which the size of the pulverized material was 5 mm, showed that the transmission loss was small at low frequencies, indicating that there was a difference in the soundproofing effect depending on the size of the pulverized material.

[0111] In addition, when comparing Examples 4 to 7 and Comparative Examples 4 to 8 according to the content of the mixture, it was found that the Examples within the content range of the components of each mixture had a greater transmission loss than the Comparative Examples, resulting in superior soundproofing effects. In particular, Comparative Example 8, which contained a smaller content of water-based bond and natural rubber latex than that of the present invention, had the lowest soundproofing effect, followed by Comparative Example 6, which contained a smaller content of natural rubber latex, showing a slightly improved soundproofing effect.

[0112] Comparative Examples 9 to 11, which had different molding pressures and pad thicknesses, also had lower transmission loss than the examples, and thus had lower soundproofing effects than the examples. On the other hand, Comparative Example 12, which had a thicker pad, had almost the same soundproofing performance as the examples, but it was found that it actually increased cost and weight, which may make installation difficult.

[0113] Therefore, it was confirmed that the soundproofing performance depends on the size of the crushed material, each content of the mixture, molding pressure, pad thickness, etc.

[0114] [Test Example 3] - Tensile strength

[0115] Test Method: Samples of soundproofing materials according to the examples and comparative examples of the present invention were prepared, and tensile strength was measured according to the ASTM D638-03 test method. Table 4 shows the soundproofing effect and tensile strength results according to the examples and comparative examples of the present invention.

[0116] Test Results: Referring to Table 4, it can be seen that the Examples were generally superior to the Comparative Examples. Specifically, the tensile strength was found to be 30 MPa or higher for all Examples. On the other hand, the Comparative Examples showed a difference of up to 7 MPa compared to the Examples. In particular, Comparative Example 11, which had the thinnest pad thickness, ranked lowest in tensile strength, followed by Comparative Example 8, which contained a small amount of water-based bond and latex.

[0117] Therefore, it was found that tensile strength is highly dependent on pad thickness. In addition, it was confirmed that factors other than pad thickness, such as molding pressure and latex content, also affect tensile strength.

[0118]

[0119] The embodiments described above are merely exemplary, and those skilled in the art to which the present invention pertains can devise various modifications and equivalent other embodiments. Therefore, the true technical protection scope of the present invention should be determined by the technical idea of ​​the invention described in the claims.

Claims

1. In the method for manufacturing soundproofing material, The first step of pretreatment is to collect the leather, wash it using a multipurpose detergent or cleaning mixture, and then dry it naturally to remove contaminants; A second step of cutting and crushing the above-mentioned pretreated leather to produce a crushed product; The third step of drying the above-mentioned pulverized material; A fourth step of producing a mixture by mixing the dried pulverized material, water-based adhesive, latex, and water in a weight ratio of 1:0.2~0.4:0.05~0.15:0.005~0.015; Step 5 of producing a molded product by pouring the mixture into a mold and press-molding it at a pressure of 60 to 100 tons; and A sixth step of drying the above-mentioned molded product; The above cleaning mixture contains water, shell powder and baking soda in a volume ratio of 100:0.05~0.25:0.03~0.

05. A method for manufacturing soundproofing material using cowhide, characterized in that the above-mentioned molded product is in the form of a pad and the thickness of the pad is 2 to 2.5 cm.

2. In paragraph 1, The second step above is, A method for manufacturing soundproofing material using faux leather, characterized in that the faux leather is cut into pieces having a thickness of 2 cm or less and a length of 20 to 30 cm using a cutter, and then the pieces are crushed into pieces having a size of 2 to 5 mm using a crusher.

3. In paragraph 1, The third step above is, A method for manufacturing soundproofing material using cowhide, characterized in that the above-mentioned crushed material is dried at 45 to 50°C for 60 to 72 hours and then naturally dried.

4. In paragraph 1, The above water-based adhesive includes a water-based bond, A method for manufacturing soundproofing material using leather, characterized in that the latex above contains natural rubber latex.

5. In paragraph 1, The above 6th step is, A method for manufacturing soundproofing material using cowhide, characterized in that the above-mentioned molded product is sequentially subjected to cold air drying, hot air drying, and natural drying.

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