TWI882326B - Artificial leather and manufacture method thereof - Google Patents

Abstract

An artificial leather is provided in the present disclosure, including: an artificial leather substrate and a temperature control layer disposed on the artificial leather substrate. The temperature control layer includes a phase-change-material microcapsule. The phase-change-material microcapsule includes a nuclear layer, a first shell layer wrapping the nuclear layer and a second shell material wrapping the first shell layer. The nuclear layer includes carboxylic ester. The carboxylic ester includes 1-acetoxyhexadecane and 1-acetoxyoctadecane. The first shell layer includes isocyanate and polyester polyol. The second shell layer includes cellulose or chitin. A manufacture method of an artificial leather is further provided in the present disclosure.

Description

Artificial leather and its manufacturing method

This disclosure relates to artificial leather and methods of making artificial leather.

With the improvement of living standards, people have higher and higher requirements for leather. Among them, the application of artificial leather has gradually broken through the limitations of genuine leather and is widely used in various industrial fields.

However, existing artificial leather is still easily affected by the ambient temperature and thus has the limitation of insufficient temperature stability.

Therefore, how to provide a method for manufacturing artificial leather with improved temperature stability is a problem to be solved.

The present disclosure provides artificial leather and a method for manufacturing the artificial leather. A temperature regulating layer is formed by placing a temperature regulating mixture on an artificial leather substrate to improve the temperature stability of the artificial leather.

According to an embodiment of the present disclosure, an artificial leather comprises an artificial leather base and a temperature regulating layer disposed on the artificial leather base. The temperature regulating layer comprises a phase change material microcapsule, and the phase change material microcapsule comprises a core layer, a first shell layer covering the core layer, and a second shell layer covering the first shell layer. The core layer comprises a carboxylic acid ester, wherein the carboxylic acid ester comprises hexadecyl formate and octadecyl formate. The first shell layer comprises isocyanate and polyester polyol. The second shell layer comprises cellulose or chitin.

In an embodiment of the present disclosure, the weight percentage of the phase change material microcapsule is 100%, the weight percentage of the core layer is 50% to 80%, the weight percentage of the first shell layer is 10% to 30%, and the weight percentage of the second shell layer is 5% to 30%.

In an embodiment of the present disclosure, the temperature adjustment layer further comprises metal oxide and graphene, and the weight ratio of the metal oxide to the graphene is 1:10 to 10:1.

In one embodiment of the present disclosure, the artificial leather substrate comprises a plurality of polypropylene fiber bundles, each of the polypropylene fiber bundles is composed of a plurality of polypropylene fibers, and the average diameter of the cross section of each polypropylene fiber is 1 μm to 10 μm.

In one embodiment of the present disclosure, the artificial leather substrate comprises polyamide fiber and polyester fiber, and the average diameter of the cross section of the polyamide fiber and the polyester fiber is 1 μm to 10 μm.

According to an embodiment of the present disclosure, a method for manufacturing artificial leather includes: providing a temperature-adjusting mixture, including: a first mixing step, mixing carboxylic acid ester and isocyanate at a first temperature; an emulsifying step, mixing carboxylic acid ester, isocyanate and polyester polyol aqueous solution at a second temperature, so that isocyanate and polyester polyol react to form a first shell layer covering a core layer containing carboxylic acid ester, and obtaining an emulsion, wherein the second temperature is greater than the first temperature; and a second mixing step, mixing cellulose with the emulsion or mixing chitin with the emulsion, so that cellulose or chitin forms a second shell layer covering the first shell layer, and obtaining a temperature-adjusting mixture; providing an artificial leather substrate; and arranging the temperature-adjusting mixture on the artificial leather substrate.

In an embodiment of the present disclosure, after the second mixing step, the graphene solution, the metal oxide dispersion and the temperature-adjusting mixture are mixed.

In one embodiment of the present disclosure, the step of providing an artificial leather substrate includes: mixing polyvinyl alcohol and polypropylene under heating conditions so that the polyvinyl alcohol and the polypropylene form a sea-island fiber cloth, wherein the sea-island fiber cloth includes polypropylene fibers and polyvinyl alcohol fibers, wherein the polypropylene fibers and the polyvinyl alcohol fibers serve as island components of the sea-island fiber cloth and sea components covering the island components, respectively; and immersing the sea-island fiber cloth in a hot water bath to dissolve and remove the polyvinyl alcohol fibers.

In an embodiment of the present disclosure, the step of mixing polyvinyl alcohol and polypropylene under heating conditions includes mixing the polyvinyl alcohol and polypropylene at a weight ratio of 1:1.

In an embodiment of the present disclosure, the step of providing an artificial leather substrate includes: using polyester and polyamide to prepare a composite fiber cloth by a composite spinning method, wherein the cross-section of the composite fiber cloth is an orange segment-like radial fan-shaped structure in which polyester fibers and polyamide fibers are arranged at intervals; and performing a fiber opening treatment on the composite fiber cloth to separate the polyester fibers and polyamide fibers from each other.

In order to implement different features of the mentioned subject matter, the following disclosure provides many different implementations. Specific examples of components, values, materials, configurations, etc. are described below to simplify the present disclosure. Of course, these are merely examples and are not restrictive. For example, in the following description, forming a first feature on or above a second feature may include an implementation in which the first feature and the second feature are formed in direct contact, and may also include an implementation in which an additional feature is formed between the first feature and the second feature so that the first feature and the second feature may not be in direct contact. In addition, the present disclosure may repeatedly refer to numbers and/or letters in various examples. This repetition is for the purpose of simplicity and clarity, and does not in itself represent the relationship between the various implementations and/or configurations discussed.

The present disclosure provides artificial leather and a method for manufacturing the artificial leather. By placing a temperature regulating mixture on an artificial leather base to form a temperature regulating layer, the temperature stability of the artificial leather is improved and the influence of the external environmental temperature change is reduced. When applied to the human body, the artificial leather can maintain a temperature range that is more comfortable for the human body for a long time.

Please refer to FIG. 1 , which shows a flow chart of a method 100 for manufacturing artificial leather, including steps S110 to S130 .

Step S110 is to provide a temperature-adjusting mixture.

In some embodiments, providing a temperature-adjusting mixture includes a first mixing step of mixing carboxylic acid ester and isocyanate at a first temperature; an emulsification step of mixing carboxylic acid ester, isocyanate and polyester polyol aqueous solution at a second temperature, so that isocyanate and polyester polyol react to form a first shell layer to cover the core layer containing carboxylic acid ester, and obtain an emulsion, wherein the second temperature is greater than the first temperature; and a second mixing step of mixing cellulose with the emulsion or mixing chitosan with the emulsion, so that cellulose or chitosan forms a second shell layer to cover the first shell layer, and obtain a temperature-adjusting mixture. By using a double-layer shell design in which the second shell layer covers the first shell layer and the core layer, the coverage rate of the phase change material microcapsule can be improved.

In some embodiments, the carboxylic acid group of the carboxylic acid ester comprises a formic acid group, an acetic acid group, a propionic acid group or a combination thereof. In some embodiments, the alcohol group of the carboxylic acid ester is a saturated alkanol having a carbon number between 10 and 20, for example, a carbon number of 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or a value in any of the foregoing intervals. In some embodiments, the carboxylic acid ester comprises hexadecyl formate and octadecyl formate. It should be emphasized that, relative to the use of a single carboxylic acid ester, when the carboxylic acid ester uses hexadecyl formate and octadecyl formate at the same time, the glass transition temperature (phase transition temperature) can be adjusted by adjusting the weight ratio of hexadecyl formate and octadecyl formate. In one embodiment, the weight ratio of cetyl formate to stearyl formate is 1:20 to 20:1, such as 1:3, 1:6, 1:9, 1:12, 1:15, 1:18, 1:20, 3:1, 6:1, 9:1, 12:1, 15:1, 18:1, 20:1, or any value in the foregoing range, wherein when the weight ratio of cetyl formate to stearyl formate is 1:9, the phase transition temperature of the synthesized temperature regulating mixture (e.g., 27.5°C to 32.5°C) is a temperature range that is more comfortable for the human body.

In some embodiments, the isocyanate includes monoisocyanate, diisocyanate or a combination thereof. The isocyanate can be used to dissolve the carboxylate and polymerize with the subsequently added polyester polyol to form a polyurethane to coat the carboxylate (core material). Therefore, the isocyanate and the polyester polyol can be collectively referred to as the first shell material (the material of the first shell layer).

In some embodiments, the polyester polyol comprises polycarbonate diol, polyethylene adipate, or a combination thereof.

In some embodiments, the weight ratio of the core material (carboxylate) to the first shell material (the sum of isocyanate and polyester polyol) is 1:1 to 20:1, such as 1:1, 4:1, 8:1, 12:1, 16:1, 20:1 or any value in the aforementioned range. If the weight ratio is too high, the coating effect of the first shell layer is not good, and if the weight ratio is too low, the core material content is too low, affecting the temperature control performance.

In some embodiments, cellulose or chitosan can be used as the second shell material, respectively, to form a second shell layer covering the first shell layer. In some embodiments, the weight ratio of the core material (carboxylate) to the first shell material (isocyanate and polyester polyol) is 2:1 to 4:1, such as 2:1, 2.25:1, 2.75:1, 3:1, 3.25:1, 3.75:1, 4:1 or values in the aforementioned intervals. In some embodiments, the weight ratio of the first shell material to the second shell material is 1:5 to 5:1, such as 1:5, 2:5, 3:5, 4:5, 1:1, 2:1, 3:1, 4:1, 5:1 or values in any of the aforementioned intervals. When the weight ratio of the core material to the first shell material is 3.75:1, and the weight ratio of the first shell material to the second shell material is 2:1, a temperature-controlled mixture having both a high thermal enthalpy value (greater than 100 joules/gram) and an excellent coverage rate (greater than 90%) can be obtained.

In some embodiments, the total weight percentage of the temperature-adjusting mixture is 100%, the weight percentage of the core material is 50% to 80% (e.g., 50%, 60%, 70%, 80% or values in between), the weight percentage of the first shell material is 10% to 30% (e.g., 10%, 20%, 30% or values in between), and the weight percentage of the second shell material is 5% to 30% (e.g., 5%, 10%, 15%, 20%, 25% or values in between). In some embodiments, the total weight percentage of the temperature-adjusting mixture is 100%, when the weight percentage of the core material is 55% to 75%, the weight percentage of the first shell material is 20% and the weight percentage of the second shell material is 10%, the phase change material microcapsule can have a coverage rate of more than 90%. In one embodiment, the total weight percentage of the temperature-adjusting mixture is 100%, when the weight percentage of the core material is 70%, the weight percentage of the first shell material is 20%, and the weight percentage of the second shell material is 10%, the phase change material microcapsule not only has a coverage rate of more than 90%, but also after being washed twice, the thermal enthalpy value can be maintained above 100 joules/gram.

In some embodiments, providing a temperature-adjusting mixture further comprises mixing a graphene solution, a metal oxide dispersion, and a temperature-adjusting mixture (cellulose and an emulsion, or chitosan and an emulsion), so that the temperature-adjusting mixture contains graphene and metal oxide in addition to the phase change material microcapsules.

It is worth emphasizing that graphene can improve the dispersibility of metal oxides. In addition, the metal oxides in the metal oxide dispersion are dispersed between the graphenes and together with the graphene form a network-like thermal conductive structure, which can further improve the longitudinal thermal conductivity.

In some embodiments, the weight ratio of the metal oxide dispersion to the graphene solution is 1:30 to 30:1, for example 1:30, 1:28, 1:25, 1:20, 1:18, 1:15, 1:12, 1:9, 1:6, 1:3, 1:1, 3:1, 6:1, 9:1, 12:1, 15:1, 18:1, 20:1 or values in between the foregoing ranges. If the weight ratio is too high, the planar thermal conductivity is limited, and if the weight ratio is too low, the longitudinal thermal conductivity is limited.

In some embodiments, the metal oxide comprises aluminum oxide, iron oxide, zinc oxide or a combination thereof. Compared with other metal oxides, the use of aluminum oxide can reduce costs.

Step S120 is to provide an artificial leather base.

In some embodiments, the artificial leather substrate can be obtained by dissolving the sea island fiber cloth or by opening the segmented fiber cloth. It is understood that compared with the conventional spinning process, the artificial leather substrate obtained by dissolving the sea island fiber cloth or by opening the segmented fiber cloth has better softness and breathability because the fibers have a finer average diameter and a smaller specific surface area.

In some embodiments, the step of providing an artificial leather substrate includes: mixing polyvinyl alcohol and polypropylene under heating conditions so that the polyvinyl alcohol and polypropylene form a sea-island fiber cloth, wherein the sea-island fiber cloth includes polypropylene fibers and polyvinyl alcohol fibers, and the polypropylene fibers and the polyvinyl alcohol fibers serve as island components of the sea-island fiber cloth and sea components covering the island components, respectively; and immersing the sea-island fiber cloth in a hot water bath to dissolve and remove the polyvinyl alcohol fibers.

In some embodiments, the artificial leather substrate comprises a plurality of polypropylene fiber bundles, each of which is composed of a plurality of polypropylene fibers, and the average diameter of the cross section of each polypropylene fiber is 1 μm to 10 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or a value in the aforementioned interval. In some embodiments, the polypropylene fiber bundle is 60 denier to 120 denier, such as 60 denier, 70 denier, 80 denier, 90 denier, 100 denier, 110 denier, 120 denier, or a value in the aforementioned interval. If the average diameter or denier is too large, the air permeability is poor, and if the average diameter or denier is too small, the structure is relatively fragile.

In addition, since the artificial leather base produced using this process is obtained by dissolving polyvinyl alcohol fibers in water rather than using organic solvents, it is more environmentally friendly.

In some embodiments, the step of mixing polyvinyl alcohol and polypropylene under heating conditions includes mixing the polyvinyl alcohol and polypropylene at a weight ratio of 1:1. If the weight ratio of polyvinyl alcohol to polypropylene is too large, the fibers are easily broken, and if the weight ratio is too small, the distribution of the island component and the sea component is irregular. In one embodiment, the step of mixing polyvinyl alcohol and polypropylene so that the polyvinyl alcohol and polypropylene form a sea-island fiber cloth includes melting the polyvinyl alcohol and polypropylene; supplying the melted polypropylene to the melted polyvinyl alcohol by pressure balance to prepare the sea-island fiber, wherein the weight ratio of the melted polyvinyl alcohol to the melted polypropylene is 1:1; and preparing the sea-island fiber cloth through a spunbonding process.

In some embodiments, the viscosity of the polyvinyl alcohol is 1 to 10 centipoise seconds (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or a value in between), and the hydrolysis rate is 95 to 100 mole percent (e.g., 95, 96, 97, 98, 99, 100, or a value in between). In some embodiments, when the viscosity of polyvinyl alcohol is 4 to 5 cmP·s and the hydrolysis rate is 98.25 mol% to 99.0 mol%, it can be easier to form a fiber, and the distribution of island components in the prepared sea-island fiber is more regular.

In some embodiments, the step of immersing the sea-island fiber fabric in a hot water bath comprises immersing the sea-island fiber fabric in a water bath at 80°C to 90°C.

In some embodiments, the step of providing an artificial leather substrate includes: using polyester and polyamide to prepare a composite fiber cloth by a composite spinning method, wherein the cross-section of the composite fiber cloth is an orange segment-like radial fan-shaped structure in which polyester fibers and polyamide fibers are arranged at intervals; and performing a fiber opening treatment on the composite fiber cloth to separate the polyester fibers and polyamide fibers from each other.

In some embodiments, the artificial leather substrate comprises polyamide fiber and polyester fiber, and the average diameter of the cross section of the polyamide fiber and the polyester fiber is 1 micron to 10 microns, such as 1 micron, 2 microns, 3 microns, 4 microns, 5 microns, 6 microns, 7 microns, 8 microns, 9 microns, 10 microns, or values in the aforementioned intervals. In some embodiments, the polyamide fiber and the polyester fiber are 60 denier to 120 denier, such as 60 denier, 70 denier, 80 denier, 90 denier, 100 denier, 110 denier, 120 denier, or values in the aforementioned intervals.

In some embodiments, the step of preparing a composite fiber cloth using polyester and polyamide in a composite spinning method includes mixing the polyester and polyamide in a weight ratio of 1:1. If the weight ratio of polyester and polyamide is too large or too small, it will be difficult to form a yarn. In one embodiment, the step of preparing a composite fiber cloth includes melting polyester and polyamide; using fan-shaped radially arranged nozzles to prepare composite fibers in a composite spinning method, wherein the weight ratio of the melted polyester and the melted polyamide is 1:1; and preparing the composite fiber into a composite fiber cloth through a spunbonding process.

In some embodiments, the step of performing a fiber opening treatment on the composite fiber fabric includes performing a hydroentanglement fiber opening treatment on the composite fiber fabric. It should be emphasized that since no organic solvent is used in the hydroentanglement fiber opening treatment, there will be no solvent residue problem, which is not only environmentally friendly, but also does not affect the fiber properties (such as strength or wear resistance).

In some embodiments, the basis weight of the artificial leather substrate is 200 g/m2 to 400 g/m2, such as 200 g/m2, 250 g/m2, 300 g/m2, 350 g/m2, 400 g/m2 or values in the aforementioned range, and as the basis weight increases, the temperature stability of the artificial leather substrate increases accordingly. However, if the basis weight is too large, the weight of the artificial leather substrate is too heavy, and when used on the human body, it will put a greater burden on the human body and the air permeability is poor. If the basis weight is too small, the structure of the artificial leather substrate is relatively fragile.

Step S130 is to place the temperature-adjusting mixture on the artificial leather substrate.

The temperature-regulating layer formed by the temperature-regulating mixture can improve the temperature stability of artificial leather. For example, if artificial leather is heated at 35°C for 30 minutes, the difference in surface temperature between the artificial leather at 10 minutes and 30 minutes is less than 1°C.

In some embodiments, the step of placing the temperature-adjusting mixture on the artificial leather substrate comprises applying the temperature-adjusting mixture on the wear-resistant layer; drying the temperature-adjusting mixture to form a temperature-adjusting layer on the wear-resistant layer; and bonding the temperature-adjusting layer and the artificial leather substrate to obtain the artificial leather. In other embodiments, the temperature-adjusting mixture can be directly applied to the artificial leather substrate.

In the following description, multiple embodiments of the present disclosure are cited to perform various analyses to verify the effectiveness of the present disclosure.

Example 1: Manufacturing of Temperature Adjustment Layer

1. Test on the compatibility ratio of carboxylic acid esters

First, according to Table 1, different ratios of hexadecanol formate and octadecyl formate (core material), a first shell material (diisocyanate and polyethylene adipate, the weight ratio of diisocyanate to polyethylene adipate is 1.5:1) and water are placed in a reaction tank, and after heating and stirring at 40°C for 1 hour, the temperature is increased by 10°C every hour until it reaches 90°C, and each interval is maintained for 1 hour. The diisocyanate of the first shell material and the polyethylene adipate undergo a polymerization reaction to form a dense mesh shell layer (first shell layer) coated with hexadecanol formate, octadecyl formate or both (core layer). Finally, a second shell material (chitosan) is added for end-capping to form a second shell layer covering the core layer and the first shell layer, thereby obtaining a mixed solution of a double-layer shell phase change material microcapsule.

In order to test the thermal properties of the mixed solutions of the phase change material microcapsules in each carboxylic acid ester ratio, the glass transition temperature (or phase transition temperature) and thermal enthalpy value of each group of phase change material microcapsules were measured using a differential scanning calorimetry (DSC). The results are simultaneously shown in Table 1.

Table 1 Group Nuclear Material First shell material (wt%) Second shell material (wt%) Glass transition temperature (°C) Thermal enthalpy (joule/gram) Hexadecyl formate (wt%) Octadecanol formate (wt%) 1 80 0 15 5 26.3-27.9 128.6 2 72 8 15 5 26.5-28.2 131.2 3 64 16 15 5 26.7-28.3 133.5 4 56 twenty four 15 5 26.7-29.6 135.8 5 48 32 15 5 26.8-31.2 137.9 6 40 40 15 5 26.9-31.5 141.2 7 32 48 15 5 27.1-31.8 142.5 8 twenty four 56 15 5 27.3-32.1 144.8 9 16 64 15 5 27.4-32.4 147.6 10 8 72 15 5 27.5-32.5 150.5 11 4 76 15 5 28.3-33.8 151.2 12 0 80 15 5 32.2-34.2 151.7

The results in Table 1 show that as the weight percentage of octadecyl formate increases, the temperature range of the glass transition temperature increases accordingly. Among Groups 1 to 12, the glass transition temperature of the phase change material microcapsule prepared in Group 10 (cetyl formate:octyl formate=1:9) falls within the most comfortable temperature range (27.5°C to 32.5°C) when in contact with the human body.

2. Compatibility test of the first shell material and the second shell material

To test the optimal ratio of the first shell material and the second shell material, the optimal carboxylic acid ester ratio (hexadecyl formate: octadecyl formate = 1:9), materials and preparation methods in point 1 were used, and according to the ratio of the first shell material and the second shell material in Table 2, phase change material microcapsules were prepared, and the initial thermal enthalpy value was measured using DSC. Then, the phase change material microcapsules in each group were sequentially subjected to water washing, reduced pressure filtration and drying treatments. After two cycles (i.e., water washing twice), the thermal enthalpy value of the phase change material microcapsules after water washing twice was measured again. Finally, according to the difference in thermal enthalpy values, the coverage rate of the phase change material microcapsules was calculated (coverage rate = thermal enthalpy value of water washing twice/initial thermal enthalpy value).

Table 2 Type Group Core material (wt%) First shell material (wt%) Second shell material (wt%) Initial enthalpy (joule/gram) Heat enthalpy after 2 washes (joule/gram) Coverage rate (%) Single shell 1 100 0 0 151.2 N/A 0 2 95 5 0 141.7 45.4 32.1 3 90 10 0 136.5 49.4 36.2 4 85 15 0 128.3 98.4 76.7 5 80 20 0 123.4 103.1 83.6 6 75 25 0 115.6 102.2 88.4 7 70 30 0 110.7 99.2 89.6 8 65 35 0 101.2 92.5 91.4 Double shell 9 75 20 5 118.2 103.5 87.6 10 70 20 10 111.3 100.5 90.3 11 65 20 15 102.5 94.9 92.6 12 60 20 20 97.4 90.7 93.2 13 55 20 25 88.1 82.5 93.7

The results in Table 2 show that when a single shell layer is used to coat the core layer, the coverage rate gradually increases as the weight percentage of the first shell material increases (Group 1 to Group 8). However, compared with the phase change material microcapsules with only a single shell layer, the phase change material microcapsules with double shell layers (for example, see Group 5, Group 9 to Group 13) have better coverage, and the coverage rate gradually increases as the weight percentage of the second shell material increases. Among Groups 9 to 13, Group 10 can have both excellent coverage and high thermal enthalpy value, so it is selected as the subsequent test group.

3. Comparison of heat dissipation efficiency of mixed solutions containing phase change material microcapsules with different ratios of metal oxides and graphene

In order to further improve the heat dissipation efficiency of the mixed solution containing the phase change material microcapsules, according to the formulation conditions in Table 3, different ratios of aluminum oxide dispersion and graphene solution were added to the mixed solution prepared according to the conditions of Group 10 in point 2, and stirred for 20 minutes to obtain a temperature-controlled mixture.

Next, after obtaining the temperature-adjusting mixtures of each group, each temperature-adjusting mixture was dried, heated to 50°C for 15 minutes, and maintained at 25°C for 10 minutes in sequence, and the temperature change of each group (relative to 25°C) was detected to evaluate the heat dissipation efficiency (△T) of the temperature-adjusting mixture. The results are summarized in Table 3.

The preparation method of the aluminum oxide dispersion and the graphene solution is as follows:

The preparation step of the alumina dispersion includes mixing alumina, a siloxane dispersant with epoxy groups and water, adding a buffer and abrasive particles, grinding the alumina to a particle size of 30 nm to 100 nm, and stably dispersing the alumina through the application of amphoteric charges and negative ions to improve the grinding efficiency. In addition, the siloxane dispersant with epoxy groups can provide stereo hindrance, making the alumina easy to disperse to avoid the aggregation and sedimentation of the alumina, wherein when the weight percentage of the alumina dispersion is 100%, the weight percentage of the alumina in the alumina dispersion is 3.5%, and the weight percentage of the siloxane dispersant with epoxy groups is 4.5%.

The preparation step of the graphene solution includes dispersing graphene powder in N-methylpyrrolidone, and performing a homogenization process on the graphene powder and N-methylpyrrolidone (generating normal stress on the graphene structure, adjusting and changing the average flake diameter of the graphene powder) to form a graphene paste; then, performing a thinning process on the graphene paste (generating plane stress on the graphene structure, changing the average thickness of the graphene powder) to form a graphene solution, thereby increasing the allowable content of graphene and improving the suspension of graphene. The average flake diameter of graphene in the graphene solution is 3 microns to 15 microns, the number of graphene layers is 5 to 10 layers, and when the weight percentage of the graphene dispersion is 100%, the weight percentage of graphene in the graphene solution is 18.5%.

Table 3 Group Mixed solution containing phase change material microcapsules (wt%) Alumina dispersion (wt%) Graphene solution (wt%) Heat dissipation efficiency (△T) 1 100 0 0 -7.5 2 94 1 5 -11.2 3 93 2 5 -14.5 4 92 3 5 -16.7 5 90 5 5 -16.4 6 85 10 5 -16.2 7 94 3 3 -10.6 8 90 3 7 -19.4 9 87 3 10 -24.6 10 82 3 15 -24.8 11 77 3 20 -25.1 12 72 3 25 -25.3

The results in Table 3 show that when the weight percentage of the graphene solution is fixed at 5% (see Groups 2 to 6), as the weight percentage of the aluminum oxide dispersion increases from 1% to 3%, the heat dissipation efficiency of the temperature-controlled mixture increases. However, when the weight percentage of the aluminum oxide dispersion is between 3% and 10%, the difference in heat dissipation efficiency is not significant.

On the other hand, when the weight percentage of the aluminum oxide dispersion is fixed at 3% (see Groups 7 to 12), as the weight percentage of the graphene solution increases from 3% to 10%, the heat dissipation efficiency of the temperature-controlled mixture increases. However, when the weight percentage of the graphene solution increases from 10% to 25%, the difference in heat dissipation efficiency is not significant.

Therefore, when the weight percentage of the aluminum oxide dispersion and the graphene solution is 3% and 10% (Group 9, the weight ratio of the aluminum oxide dispersion and the graphene solution is 3:10), even if the content of the aluminum oxide dispersion or the graphene solution is increased, the heat dissipation efficiency cannot be significantly improved. In other words, Group 9 is a formula that uses the least amount of aluminum oxide dispersion and graphene solution to achieve the best heat dissipation efficiency.

Example 2: Artificial leather including a temperature regulating layer

2.1. Manufacturing method of artificial leather

First, the mixed solution or the temperature-adjusting mixture (mixed solution + alumina dispersion + graphene solution) containing the phase change material microcapsules prepared according to the aforementioned Example 1 is applied as a temperature-adjusting layer on the wear-resistant layer and dried and cured. Then, the exposed side of the temperature-adjusting layer is bonded to the artificial leather substrate [for example, obtained by dissolving the island-shaped fiber cloth (hereinafter referred to as the "island-shaped fiber cloth dissolution method"), or obtained by opening the orange segment-shaped fiber cloth (hereinafter referred to as the "orange segment-shaped fiber cloth opening method")] by adhesive bonding, and then dried and aged to obtain artificial leather.

Each stage step is observed under an electron microscope, wherein Figures 2A to 2C are electron microscope images of phase change material microcapsules, artificial leather substrate, and artificial leather, respectively, wherein it can be observed that the phase change material microcapsules are distributed on the fibers in the artificial leather substrate.

2.2 Artificial leather made by the island-type fiber cloth dissolution method

2.2.1. Manufacturing condition test

First, polyvinyl alcohol (sea component) and polypropylene (island component) are heated to a flowable molten state, and the two are made to flow to the spinning mouth through the pipeline, and then, according to the weight ratio in Table 4, the supply amount is adjusted to achieve pressure balance, and the melted polypropylene (island component) is supplied to the melted polyvinyl alcohol (sea component) at 200°C to prepare sea-island type fibers (including island components and sea components covering island components). By observing the spinning properties, strength and fiber cross-section of the spun filaments, the better type of polyvinyl alcohol that can form sea-island type fibers and the appropriate weight ratio of polypropylene to polyvinyl alcohol are tested, and the results are summarized in Table 4.

Table 4 Composition (island component + sea component) Weight ratio (island component:sea component) Spinning condition Filamentation Fiber section Test Example 1 Polypropylene + Polyvinyl alcohol 1 1:1 Unable to form silk Clearly separable Test Example 2 Polypropylene + Polyvinyl alcohol 2 1:1 Spinnable The distribution of island components is irregular Test Example 3 Polypropylene + Polyvinyl alcohol 3 1:1 Very easy to break Clearly separable Test Example 4 Polypropylene + Polyvinyl alcohol 4 1:1 Spinnable Clearly separable Test Example 5 Polypropylene + Polyvinyl alcohol 4 2:3 Easy to break Clearly separable Test Example 6 Polypropylene + Polyvinyl alcohol 4 3:7 Easy to break Clearly separable Note 1: Polyvinyl alcohol 1 is a polyvinyl alcohol produced by Kuraray, with the trade name MOWIFLEX™ H15. The viscosity of polyvinyl alcohol 1 is 200 cm·s (in a 4% solution at 20°C), and the hydrolysis rate is more than 99 mol%. Note 2: Polyvinyl alcohol 2 and polyvinyl alcohol 3 are both products of Changchun Company, with the trade names polyvinyl alcohol BF-03 and polyvinyl alcohol BF-05, respectively. The difference between the two lies in the viscosity and hydrolysis rate. The viscosity of polyvinyl alcohol BF-03 is 3 cm·s to 4 cm·s, and the hydrolysis rate is 98 mol% to 98.8 mol%. The viscosity of polyvinyl alcohol BF-05 is 5 cm·s to 6 cm·s, and the hydrolysis rate is 98.5 mol% to 99.2 mol%. Therefore, the viscosity and hydrolysis rate range of polyvinyl alcohol 3 are greater than those of polyvinyl alcohol 2. Note 3: Polyvinyl alcohol 4 is a mixture of polyvinyl alcohol 2 and polyvinyl alcohol 3 in a weight ratio of 1:1. Note 4: When the weight ratio of polypropylene to polyvinyl alcohol is 1:1 (such as test example 4), the number of spinning holes is 24 holes, and the number of islands is 37 islands, the whole bundle of fibers is 60 denier to 120 denier, and the diameter of a single fiber is approximately between 2.28 μm and 3.24 μm.

The results in Table 4 show that the spinning process can be successfully completed only when the combination of polyvinyl alcohol 2 and polypropylene is used (see Test Example 2 and Test Example 4). However, the distribution of the island components is irregular when the combination of polyvinyl alcohol 2 and polypropylene is used alone (Test Example 2). Polyvinyl alcohol 4 (Test Example 4, including polyvinyl alcohol 2 and polyvinyl alcohol 3 with higher viscosity and hydrolysis rate) is used to form regularly distributed island components.

In addition, by further comparing the properties of the filaments produced by different weight ratios of polypropylene and polyvinyl alcohol 4 in Test Examples 4 to 6, it was found that only when the weight ratio of polyvinyl alcohol 4 to polypropylene was 1:1 (Test Example 4), island-shaped fibers with sufficient fiber strength and resistance to breakage could be obtained.

2.2.2 Thermal enthalpy test

After preparing the island-shaped fiber under the conditions of Test Example 4 in the above-mentioned 2.2.2, the island-shaped fiber is prepared into an island-shaped fiber cloth comprising polypropylene fiber (island) and polyvinyl alcohol fiber (sea) by a spunbond method. Then, the island-shaped fiber cloth is immersed in a hot water bath at 80°C to 90°C to dissolve and remove the polyvinyl alcohol fiber, and then the fiber cloth is dried to serve as an artificial leather substrate.

Next, according to the method for manufacturing artificial leather described in Example 2.1 (in the preparation process of the temperature regulating layer, the preferred group formula in Example 1 is selected. That is, the weight percentage of the mixed solution is 87%, the weight percentage of the aluminum oxide dispersion is 3%, the weight percentage of the graphene solution is 10%, wherein the hexadecyl formate in the core material: the octadecyl formate = 1:9, the first shell material: the second shell material = 2:1, wherein the core-shell ratio is adjusted to 85%), and different artificial leather thicknesses, wet weights of the temperature regulating layer, and core-shell ratios (weight ratios of the core layer to the shell layer) of the phase change material microcapsules of the temperature regulating layer in Table 5, multiple groups of artificial leathers containing the temperature regulating layer are prepared, and a differential scanning calorimetry (DSC) is used. The thermal enthalpy of each group of artificial leather was measured, and the results are shown in Table 5.

Table 5 Test Example 1 Test Example 2 Test Example 3 Test Example 4 Thickness of artificial leather (mm) 0.7 0.7 0.76 0.76 Wet weight of thermostatic layer (g/yd) 45 50 45 50 Core-shell ratio of phase change material microcapsules (weight percentage; wt%) 85 85 85 85 Thermal enthalpy (joule/gram) 1.2-1.3 1.5-1.6 1.6-1.7 1.8-1.9

The results in Table 5 show that, at the same artificial leather thickness and core-shell ratio of the phase change material microcapsule, as the wet weight of the temperature regulating layer increases, the thermal enthalpy value of the artificial leather increases, indicating that the temperature regulating layer can increase the thermal enthalpy value of the artificial leather and has a better temperature retention effect.

2.3. Artificial leather made by the split-segment fiber cloth open fiber method

2.3.1. Manufacturing condition test

First, melt polyester and polyamide, then set the weight ratio of polyester to polyamide to 1:1 (this ratio can successfully form yarn), and arrange the nozzles in a fan-shaped radial shape to prepare composite fibers in a composite spinning method, so that the cross-section of the composite fiber is an orange segment-shaped radial fan-shaped with polyester fibers and polyamide fibers arranged at intervals. Then, prepare the composite fiber into a composite fiber cloth (orange segment-shaped fiber cloth) through a spunbond method. Then, use a hydroentanglement method to split the polyester fibers and polyamide fibers in the orange segment-shaped fiber cloth from each other, and then dry the fiber cloth to serve as the artificial leather base.

Next, basically according to the manufacturing method of artificial leather described in Example 2.1, multiple groups of artificial leathers including a temperature regulating layer were prepared, wherein the conditions of the artificial leather base weight, artificial leather thickness, fiber diameter after fiber opening, wet weight of the temperature regulating layer, and core-shell ratio (weight ratio of the core layer to the shell layer) of the phase change material microcapsule of the temperature regulating layer of each group are shown in Table 6.

Table 6 Test Example 1 Test Example 2 Test Example 3 Test Example 4 Basis weight of artificial leather substrate (g/m2) 264.5 297.6 388.5 625.0 Thickness of artificial leather (mm) 0.56 0.63 0.76 1.2 Fiber diameter after opening (mm) 4.93 4.72 4.75 4.84 Wet weight of thermostatic layer (g/yd) 50 50 50 50 Core-shell ratio of phase change material microcapsules (weight percentage; wt%) 85 85 85 85

Table 6 shows that as the basis weight of the artificial leather base increases, the thickness of the artificial leather also increases. When the thickness of the artificial leather is 1.2 mm, the basis weight of the artificial leather base is 625.0 g/m2, which is too heavy. Therefore, only Test Examples 1 to 3 and blank leather without a temperature regulating layer (Comparative Example 1, polyurethane leather without a temperature regulating layer) were selected for subsequent physical property tests. The results are shown in Table 7.

The test methods for the properties in Table 7 are described below. Softness is the value obtained by testing with a softness tester ST-300. Air permeability is the value obtained by testing according to the standard test method for air permeability ASTM D737. Abrasion resistance is the value obtained by testing according to the standard test method for abrasion resistance ASTM D4966. Tensile strength is the value obtained by testing according to the standard test method for tension JIS L1096, where the longitudinal tensile force is 84.2 N/cm and the transverse tensile force is 64.2 N/cm. The temperature difference is measured by using a 35°C heat source for 30 minutes, and using a thermal imager to detect the surface temperature difference between the blank group (the group without comparative example 1 or test examples 1 to 3) and comparative example 1 or test examples 1 to 3. The constant temperature is measured by using a 35°C heat source to heat comparative example 1 or test examples 1 to 3 for 30 minutes, and using a thermal imager to detect the surface temperature of each group, and then calculating the temperature difference between each group heated for 10 minutes and heated for 30 minutes.

Table 7 Comparative example 1 Test Example 1 Test Example 2 Test Example 3 softness 3-4 6 6.2 6.2 Air permeability (cubic feet/minute) <0.2 0.5 0.59 0.58 Wear resistance (times) 8000 15000 16590 16500 Tensile strength (kg/5cm) Vertical: 30-40 Horizontal: 25-30 Vertical: 69.5 Horizontal: 51.2 Vertical: 74.1 Horizontal: 50.6 Vertical: 84.2 Horizontal: 64.2 Holding temperature difference (°C) ＜1 3.5 3.5 3.5 Temperature stability (°C) 5.8 0.8 0.8 0.5

The results in Table 5 show that, compared with Comparative Example 1 (polyurethane leather without a temperature regulating layer), Test Examples 1 to 3 (artificial leather made by the split fiber cloth open fiber method and coated with a temperature regulating layer) are all superior in softness, air permeability, wear resistance and tensile strength, and have a smaller temperature difference and better temperature stability. Among Test Examples 1 to 3 with different basis weights, Test Example 3 with the largest basis weight (388.5 g/m2) exhibits better temperature stability.

2.4. Heating, cooling, and temperature retention tests of artificial leather

2.4.1. Temperature rise test

In order to test the temperature change trend of artificial leather provided with a temperature regulating layer (leather sample 1 in which the temperature regulating layer contains 75wt% of phase change material microcapsules, and leather sample 2 in which the temperature regulating layer contains 85wt% of phase change material microcapsules, wherein the core-shell ratio of the phase change material microcapsules is 85:15) under heating conditions, leather sample 1 and leather sample 2 were heated using an 80-watt halogen lamp, and the temperature was measured at specific time points. A blank leather without the addition of the temperature regulating mixture was used as a control group, and the temperature change trend was summarized in Figure 3.

In addition, since the temperature trends of artificial leathers prepared by the "island fiber cloth dissolution method" and the "orange segment fiber cloth opening method" are not much different, the series of experiments from Point 2.4.1 to Point 2.4.3 are represented by leather samples 1 and leather samples 2 prepared by the "orange segment fiber opening method".

The results in Figure 3 show that, compared to the blank leather, leather sample 1 and leather sample 2 have better temperature buffering effects and can maintain a longer temperature range within the human body comfort zone. Between leather sample 1 and leather sample 2, leather sample 2, which has a higher content of the temperature regulating mixture, has a better buffering effect.

2.4.2. Cooling test

In order to compare the temperature change of artificial leather with or without a temperature regulating layer under cooling conditions, blank leather, leather sample 1, and leather sample 2 were heated to about 35°C, then left at room temperature to cool down, and the temperature was measured at specific time points. The temperature change trend is summarized in Figure 4.

The results in Figure 4 show that, compared to the blank leather, leather sample 1 and leather sample 2 can cool down at a slower rate and also have a better temperature buffering effect. Between leather sample 1 and leather sample 2, leather sample 2, which has a higher content of the temperature regulating mixture, also has a better buffering effect.

2.4.3. Temperature retention test

In order to compare the temperature retention of artificial leather with and without a temperature regulating layer, blank leather (polyurethane leather without a temperature regulating layer) and leather sample 2 were continuously heated using an 80-watt halogen lamp, and the temperature was measured at specific time points. The temperature change trend is summarized in Figure 5.

The results in Figure 5 show that after 40 minutes of stable heating, the temperature difference between the blank leather and the leather sample 2 is 3.8°C. That is, compared with the blank leather, the temperature variation of the leather sample 2 with the temperature regulating layer is smaller, the temperature stability is better, and it has a better temperature retention effect.

The features of some embodiments are summarized above so that those skilled in the art can better understand the perspective of the present disclosure. Those skilled in the art should understand that they can easily use the present disclosure as a basis for designing or modifying other processes and structures to achieve the same purpose and/or achieve the same advantages as the embodiments described herein. Those skilled in the art should also understand that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions and modifications can be made without departing from the spirit and scope of the present disclosure.

100: Manufacturing method S110, S120, S130: Steps

Various aspects of the present disclosure are best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that various features are not drawn to scale in accordance with standard methods in the industry. In fact, the sizes of various features may be arbitrarily increased or decreased for clarity of discussion. FIG. 1 shows a flow chart of a method for making artificial leather. FIG. 2A to FIG. 2C show electron microscope images of phase change material microcapsules, artificial leather substrates, and artificial leather, respectively. FIG. 3 shows a temperature change trend of artificial leather under an external temperature increase. FIG. 4 shows a temperature change trend of artificial leather under an external temperature decrease. FIG. 5 shows a temperature change trend of artificial leather under an external temperature increase for a long time.

Domestic storage information (please note in the order of storage institution, date, and number) None Foreign storage information (please note in the order of storage country, institution, date, and number) None

100: Manufacturing method

S110, S120, S130: Steps

Claims (10)

An artificial leather comprises: an artificial leather base; and a temperature regulating layer disposed on the artificial leather base, wherein the temperature regulating layer comprises a phase change material microcapsule, and the phase change material microcapsule comprises: a core layer comprising a carboxylic acid ester, wherein the carboxylic acid ester comprises hexadecyl formate and octadecyl formate; a first shell layer covering the core layer, comprising isocyanate and polyester polyol; and a second shell layer covering the first shell layer, comprising cellulose or chitin. The artificial leather as described in claim 1, wherein the weight percentage of the phase change material microcapsule is 100%, the weight percentage of the core layer is 50% to 80%, the weight percentage of the first shell layer is 10% to 30%, and the weight percentage of the second shell layer is 5% to 30%. The artificial leather as described in claim 1, wherein the temperature regulating layer further comprises metal oxide and graphene, and the weight ratio of the metal oxide to the graphene is 1:10 to 10:1. The artificial leather as described in claim 1, wherein the artificial leather substrate comprises a plurality of polypropylene fiber bundles, each of the polypropylene fiber bundles is composed of a plurality of polypropylene fibers, and the average diameter of the cross section of each of the polypropylene fibers is 1 micrometer to 10 micrometers. The artificial leather as described in claim 1, wherein the artificial leather substrate comprises polyamide fiber and polyester fiber, and the average diameter of the cross section of the polyamide fiber and the polyester fiber is 1 micron to 10 microns. A method for manufacturing artificial leather comprises: providing a temperature-adjusting mixture, comprising: a first mixing step, mixing carboxylic acid ester and isocyanate at a first temperature, wherein the carboxylic acid ester comprises hexadecyl formate and octadecyl formate; an emulsifying step, mixing the carboxylic acid ester, the isocyanate and a polyester polyol aqueous solution at a second temperature, so that the isocyanate reacts with the polyester polyol to form a first shell layer covering a core layer comprising the carboxylic acid ester, and obtaining an emulsion, wherein the second temperature is greater than the first temperature; and a second mixing step, mixing cellulose with the emulsion or mixing chitin with the emulsion, so that the cellulose or the chitin forms a second shell layer covering the first shell layer, and obtaining the temperature-adjusting mixture; providing an artificial leather substrate; and arranging the temperature-adjusting mixture on the artificial leather substrate. The method for manufacturing artificial leather as described in claim 6, wherein after the second mixing step, the graphene solution, the metal oxide dispersion and the temperature-adjusting mixture are mixed. The method for manufacturing artificial leather as described in claim 6, wherein the step of providing the artificial leather substrate comprises: mixing polyvinyl alcohol and polypropylene under heating conditions so that the polyvinyl alcohol and the polypropylene form a sea-island fiber cloth, wherein the sea-island fiber cloth comprises the polypropylene fiber and the polyvinyl alcohol fiber, wherein the polypropylene fiber and the polyvinyl alcohol fiber serve as the island component of the sea-island fiber cloth and the sea component covering the island component, respectively; and immersing the sea-island fiber cloth in a hot water bath to dissolve and remove the polyvinyl alcohol fiber. The method for manufacturing artificial leather as described in claim 8, wherein the step of mixing the polyvinyl alcohol and the polypropylene under heating conditions comprises mixing the polyvinyl alcohol and the polypropylene at a weight ratio of 1:1. The method for manufacturing artificial leather as described in claim 6, wherein the step of providing the artificial leather substrate comprises: using polyester and polyamide to prepare a composite fiber cloth by a composite spinning method, wherein the cross-section of the composite fiber cloth is an orange segment-shaped radial fan-shaped with polyester fibers and polyamide fibers arranged at intervals; and performing a fiber opening treatment on the composite fiber cloth so that the polyester fibers and the polyamide fibers are separated from each other.

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