High-breathability sponge foam material and preparation method thereof

Abstract

The invention discloses a high-breathability sponge foam material and a preparation method thereof, and belongs to the technical field of sponge material preparation, the high-breathability sponge foam material comprises the following components by weight: 100 parts of modified polyisocyanate, 150-200 parts of polyol, 10-50 parts of a first modified monomer, 4-18 parts of a second modified monomer, 2-5 parts of a foaming agent, 0.5-3 parts of silicone oil, and 0.5-2 parts of a catalyst; the first modified monomer is obtained by performing Knoevenagel condensation on diacetyl piperazine diketone and diethoxy benzaldehyde, then performing acylation with trifluoromethanesulfonic anhydride to form ester, then reacting with pyridine to generate pyridinium salt, performing ring formation to obtain ethoxy phenyl grafted pyrazino indolizine, and finally performing ether cracking; the second modified monomer is 2, 7-dihydroxy-9-fluorenone; on the basis of polyurethane, by introducing the first modified monomer and the second modified monomer, the high-breathability sponge foam material with good mechanical properties is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of sponge material preparation, in particular to a highly breathable sponge foam material and a preparation method thereof. Background Art

[0002] Sponge foam materials are widely used in a variety of fields, and their core performance indicators include air permeability and mechanical strength. The air permeability of sponge materials depends on high porosity and pore connectivity. When the porosity exceeds 80%, gas can diffuse efficiently through tortuous channels, but high porosity directly weakens the material's load-bearing capacity. According to the Gibson-Ashby model, the elastic modulus of porous materials is cubically related to the relative density, while the compressive strength is proportional to the square of the relative density. This means that when the porosity increases from 50% to 90%, the theoretical strength will drop by about 90%. Experimental data show that for every 10% increase in the porosity of polyurethane sponge, the compressive strength will decrease by an average of 40%-60%. Therefore, for high-density sponge materials, they usually have smaller pores. Due to their compact structure and smaller pores, they can usually provide better support and may be more physically durable, but this also restricts air flow, obstructing the gas permeation path and significantly deteriorating the air permeability; while low-density sponge materials have larger pores, allowing more air circulation, thereby improving the air permeability, but due to their pore structure, low-density sponge materials may be more susceptible to deformation or breakage after long-term use. Summary of the Invention

[0003] In view of the above problems, the present invention provides a highly breathable sponge foam material and a preparation method thereof.

[0004] The purpose of the present invention is achieved by adopting the following technical solutions:

[0005] A highly breathable sponge foam material, comprising the following components in parts by weight:

[0006] 100 parts of modified polyisocyanate, 150-200 parts of polyol, 10-50 parts of first modified monomer, 4-18 parts of second modified monomer, 2-5 parts of foaming agent, 0.5-3 parts of silicone oil, 0.5-2 parts of catalyst;

[0007] The preparation method of the first modified monomer comprises the following steps:

[0008] (1) Weighing 1,4-diacetylpiperazine-2,5-dione and 3,5-diethoxybenzaldehyde respectively and dissolving them in dimethylformamide solvent, adding triethylamine, heating to 100-120°C and stirring to react for 12-20 hours, cooling after the reaction is completed, adding water to dilute the reaction system, separating the precipitate, washing, and drying to obtain product A;

[0009] (2) dissolving the product A in dichloromethane solvent, adding trifluoromethanesulfonic anhydride and pyridine in an ice-water bath, stirring and mixing thoroughly, and then stirring and reacting at room temperature for 12-20 hours, adding hexane to dilute the reaction system, separating the precipitate, washing, and drying to obtain product B; dissolving the product B in toluene solvent, adding pyridine, heating to 100-120°C and stirring and reacting for 12-20 hours, cooling after the reaction is completed, adding hexane to dilute the reaction system, separating the precipitate, washing, and drying to obtain product C;

[0010] (3) dissolving the product C in a mixed solvent of dimethylformamide and ethylene glycol dimethyl ether, adding tetramethylguanidine, heating to 100-120° C. under a protective atmosphere and stirring the mixture for 12-20 hours, cooling after completion of the reaction, concentrating under reduced pressure, and then purifying on a silica gel column to obtain product D; dissolving the product D in a tetrahydrofuran solvent, adding boron tribromide, stirring the mixture for 2-8 hours under a protective atmosphere and at room temperature, adding dilute hydrochloric acid and hexane to dilute the reaction system, separating the precipitate, washing, and drying the mixture;

[0011] The second modified monomer is 2,7-dihydroxy-9-fluorenone.

[0012] In some preferred embodiments, the modified polyisocyanate is one or more of modified MDI-8019, modified MDI-2412, and modified MDI-5412.

[0013] In some preferred embodiments, the polyol is a mixture of a polyether polyol and a polymer polyol in a mass ratio of (2-3):1; the polyether polyol includes one or more of the models POLYOL-TP360, POLYOL-TP390, and POLYOL-TP440; and the polymer polyol includes one or more of the models POP-36 / 28, POP-36 / 30, and POP-36 / 45.

[0014] In some preferred embodiments, the mass ratio of the 1,4-diacetylpiperazine-2,5-dione, the 3,5-diethoxy-benzaldehyde, and the triethylamine in step (1) is 10:(10-14):(20-30).

[0015] In some preferred embodiments, in step (2), the mass ratio of the product A to the trifluoromethanesulfonic anhydride and the pyridine is 1:(1.8-2.4):(0.5-0.7); the mass ratio of the product B to the pyridine is 1:(1.2-2).

[0016] In some preferred embodiments, in step (3), the mass ratio of the product C to the tetramethylguanidine is 1:(8-13); the mass ratio of the product D to the boron tribromide is 1:(0.4-0.6).

[0017] In some preferred embodiments, the foaming agent is deionized water.

[0018] In some preferred embodiments, the silicone oil is polyether-modified silicone oil, including one or more of models H-204, MSD-9103, MSD-9102, and OFX-0190.

[0019] In some preferred embodiments, the catalyst is an organotin catalyst, including stannous octoate or dibutyltin dilaurate.

[0020] The second aspect of the present invention is to provide a method for preparing the highly breathable sponge foam material, comprising the following steps:

[0021] The polyol, the first modified monomer, the second modified monomer, the blowing agent and the silicone oil are weighed in proportion and added to a stirrer, stirred at room temperature until uniform, heated to 30-50°C, and the modified polyisocyanate and the catalyst are added and stirred at high speed, and then transferred to a preheated mold at a temperature of 50-70°C, kept warm for 5-10 minutes, formed in the mold for 5-10 minutes, and then demolded to obtain the highly breathable sponge foam material.

[0022] In some preferred embodiments, the high-speed stirring has a stirring speed of 1200 r / min and a stirring time of 10-20 s.

[0023] The beneficial effects of the present invention are:

[0024] In view of the problem that sponge materials in the prior art are difficult to balance breathability and mechanical properties, the present invention obtains a highly breathable sponge foam material with good mechanical properties by introducing a first modified monomer and a second modified monomer. Specifically, based on a polyurethane sponge prepared from polyisocyanate and polyol as raw materials, the present invention simultaneously introduces pyrazinodolizine and fluorenone structures into the polyurethane sponge through the reaction of the first / second active monomer with the polyisocyanate, uses pyrazinodolizine as an electron-rich donor, and uses fluorenone as an electron-deficient acceptor to produce a strong complexation, forming a host-guest complex in the polyurethane polymer chain. The composite cross-linking system effectively improves the mechanical properties of the polymer foaming system, wherein the first modified monomer is 1,4-diacetylpiperazine-2,5-dione and 3,5-diethoxy-benzaldehyde as raw materials. Under alkaline conditions, the aldehyde group and the methylene group in 1,4-diacetylpiperazine-2,5-dione undergo Knoevenagel condensation to obtain product A, which is then acylated with trifluoromethanesulfonic anhydride to form an ester to obtain product B; product B reacts with pyridine to form a pyridinium salt, which is then cyclized to obtain ethoxyphenyl-grafted pyrazinoindolizine, which is finally obtained after ether cleavage. DETAILED DESCRIPTION

[0025] The present invention is further described with reference to the following examples.

[0026] Example 1

[0027] A highly breathable sponge foam material, comprising the following components in parts by weight:

[0028] 100 parts of modified polyisocyanate, 160 parts of polyol, 25 parts of first modified monomer, 10 parts of second modified monomer, 4 parts of deionized water, 2 parts of silicone oil, 1 part of catalyst;

[0029] The modified polyisocyanate is modified MDI-8019 (Wanhua);

[0030] The polyol is a mixture of polyether polyol and polymer polyol in a mass ratio of 2.4:1; the model of the polyether polyol is POLYOL-TP360; the model of the polymer polyol is POP-36 / 28;

[0031] The first modified monomer is prepared by the following method:

[0032] (1) Weighing 1,4-diacetylpiperazine-2,5-dione (CAS No.: 3027-05-2) and 3,5-diethoxy-benzaldehyde (CAS No.: 120355-79-5) respectively and dissolving them in dimethylformamide solvent, adding triethylamine, heating to 100°C and stirring to react for 14 hours, cooling after the reaction is completed, adding water to dilute the reaction system, separating the precipitate, washing, and drying to obtain product A; the mass ratio of the 1,4-diacetylpiperazine-2,5-dione to the 3,5-diethoxy-benzaldehyde and the triethylamine is 10:12:24;

[0033] (2) dissolving the product A in dichloromethane solvent, adding trifluoromethanesulfonic anhydride and pyridine in an ice-water bath, stirring and mixing thoroughly, and then stirring and reacting at room temperature for 14 hours, adding hexane to dilute the reaction system, separating the precipitate, washing, and drying to obtain product B; dissolving the product B in toluene solvent, adding pyridine, heating to 100°C and stirring and reacting for 14 hours, cooling after the reaction is completed, adding hexane to dilute the reaction system, separating the precipitate, washing, and drying to obtain product C; the mass ratio of the product A to the trifluoromethanesulfonic anhydride and the pyridine is 1:2:0.57; the mass ratio of the product B to the pyridine is 1:1.5;

[0034] (3) The product C is dissolved in a mixed solvent of dimethylformamide and ethylene glycol dimethyl ether, tetramethylguanidine is added, the temperature is raised to 100°C under a protective atmosphere and the mixture is stirred and reacted for 14 hours. After the reaction is completed, the mixture is cooled, concentrated under reduced pressure, and purified on a silica gel column. The mobile phase is a mixed solution of hexane and dichloromethane (v / v=1 / 9) to obtain product D; the product D is dissolved in tetrahydrofuran solvent, boron tribromide is added, the mixture is stirred and reacted for 4 hours under a protective atmosphere and room temperature. After the reaction is completed, 0.01 mol / L dilute hydrochloric acid and hexane (v / v=1 / 10) are added to dilute the reaction system, the precipitate is separated, washed, and dried to obtain the product; the mass ratio of the product C to the tetramethylguanidine is 1:11; the mass ratio of the product D to the boron tribromide is 1:0.46;

[0035] The second modified monomer is 2,7-dihydroxy-9-fluorenone (CAS No.: 42523-29-5);

[0036] The silicone oil is polyether modified silicone oil, model H-204;

[0037] The catalyst is an organotin catalyst, model T-9 (stannous octoate);

[0038] The preparation method of the highly breathable sponge foam material comprises the following steps:

[0039] The polyol, the first modified monomer, the second modified monomer, deionized water and silicone oil are weighed in proportion and added to a stirrer, stirred at room temperature until uniform, heated to 45°C, added with modified polyisocyanate and a catalyst and stirred at high speed, and then transferred to a preheated mold at a preheating temperature of 65°C, kept warm for 5 minutes, formed in the mold for 5 minutes, and then demolded to obtain the highly breathable sponge foam material; the stirring speed of the high-speed stirring is 1200 r / min, and the stirring time is 14 seconds.

[0040] Example 2

[0041] A highly breathable sponge foam material, comprising the following components in parts by weight:

[0042] 100 parts of modified polyisocyanate, 150 parts of polyol, 35 parts of first modified monomer, 13 parts of second modified monomer, 5 parts of deionized water, 3 parts of silicone oil, 1.5 parts of catalyst;

[0043] The modified polyisocyanate is modified MDI-2412 (Shanghai Yexing);

[0044] The polyol is a mixture of polyether polyol and polymer polyol in a mass ratio of 3:1; the model of the polyether polyol is POLYOL-TP390; the model of the polymer polyol is POP-36 / 30;

[0045] The first modified monomer is prepared by the following method:

[0046] (1) Weighing 1,4-diacetylpiperazine-2,5-dione and 3,5-diethoxy-benzaldehyde respectively and dissolving them in dimethylformamide solvent, adding triethylamine, heating to 100°C and stirring to react for 14 hours, cooling after the reaction is completed, adding water to dilute the reaction system, separating the precipitate, washing, and drying to obtain product A; the mass ratio of the 1,4-diacetylpiperazine-2,5-dione to the 3,5-diethoxy-benzaldehyde and the triethylamine is 10:14:20;

[0047] (2) dissolving the product A in dichloromethane solvent, adding trifluoromethanesulfonic anhydride and pyridine in an ice-water bath, stirring and mixing thoroughly, and then stirring and reacting at room temperature for 14 hours, adding hexane to dilute the reaction system, separating the precipitate, washing, and drying to obtain product B; dissolving the product B in toluene solvent, adding pyridine, heating to 100°C and stirring and reacting for 14 hours, cooling after the reaction is completed, adding hexane to dilute the reaction system, separating the precipitate, washing, and drying to obtain product C; the mass ratio of the product A to the trifluoromethanesulfonic anhydride and the pyridine is 1:1.8:0.5; the mass ratio of the product B to the pyridine is 1:2;

[0048] (3) The product C is dissolved in a mixed solvent of dimethylformamide and ethylene glycol dimethyl ether, tetramethylguanidine is added, the temperature is raised to 100°C under a protective atmosphere and the mixture is stirred and reacted for 14 hours. After the reaction is completed, the mixture is cooled, concentrated under reduced pressure, and purified on a silica gel column. The mobile phase is a mixed solution of hexane and dichloromethane (v / v=1 / 9) to obtain product D; the product D is dissolved in tetrahydrofuran solvent, boron tribromide is added, the mixture is stirred and reacted for 4 hours under a protective atmosphere and room temperature. After the reaction is completed, 0.01 mol / L dilute hydrochloric acid and hexane (v / v=1 / 10) are added to dilute the reaction system, the precipitate is separated, washed, and dried to obtain the product; the mass ratio of the product C to the tetramethylguanidine is 1:8; the mass ratio of the product D to the boron tribromide is 1:0.5;

[0049] The second modified monomer is 2,7-dihydroxy-9-fluorenone;

[0050] The silicone oil is polyether modified silicone oil, model H-204;

[0051] The catalyst is an organotin catalyst, model T-9 (stannous octoate);

[0052] The preparation method of the highly breathable sponge foam material comprises the following steps:

[0053] The polyol, the first modified monomer, the second modified monomer, deionized water and silicone oil are weighed in proportion and added to a stirrer, stirred at room temperature until uniform, heated to 45°C, added with modified polyisocyanate and a catalyst and stirred at high speed, and then transferred to a preheated mold at a preheating temperature of 65°C, kept warm for 5 minutes, formed in the mold for 5 minutes, and then demolded to obtain the highly breathable sponge foam material; the stirring speed of the high-speed stirring is 1200 r / min, and the stirring time is 14 seconds.

[0054] Example 3

[0055] A highly breathable sponge foam material, comprising the following components in parts by weight:

[0056] 100 parts of modified polyisocyanate, 160 parts of polyol, 10 parts of second modified monomer, 4 parts of deionized water, 2 parts of silicone oil, 1 part of catalyst;

[0057] The modified polyisocyanate is modified MDI-8019 (Wanhua);

[0058] The polyol is a mixture of polyether polyol and polymer polyol in a mass ratio of 2.4:1; the model of the polyether polyol is POLYOL-TP360; the model of the polymer polyol is POP-36 / 28;

[0059] The second modified monomer is 2,7-dihydroxy-9-fluorenone;

[0060] The silicone oil is polyether modified silicone oil, model H-204;

[0061] The catalyst is an organotin catalyst, model T-9 (stannous octoate);

[0062] The preparation method of the highly breathable sponge foam material is the same as that in Example 1.

[0063] Example 4

[0064] A highly breathable sponge foam material, comprising the following components in parts by weight:

[0065] 100 parts of modified polyisocyanate, 160 parts of polyol, 25 parts of first modified monomer, 4 parts of deionized water, 2 parts of silicone oil, 1 part of catalyst;

[0066] The modified polyisocyanate is modified MDI-8019 (Wanhua);

[0067] The polyol is a mixture of polyether polyol and polymer polyol in a mass ratio of 2.4:1; the model of the polyether polyol is POLYOL-TP360; the model of the polymer polyol is POP-36 / 28;

[0068] The first modified monomer is prepared by the following method:

[0069] (1) Weighing 1,4-diacetylpiperazine-2,5-dione (CAS No.: 3027-05-2) and 3,5-diethoxy-benzaldehyde (CAS No.: 120355-79-5) respectively and dissolving them in dimethylformamide solvent, adding triethylamine, heating to 100°C and stirring to react for 14 hours, cooling after the reaction is completed, adding water to dilute the reaction system, separating the precipitate, washing, and drying to obtain product A; the mass ratio of the 1,4-diacetylpiperazine-2,5-dione to the 3,5-diethoxy-benzaldehyde and the triethylamine is 10:12:24;

[0070] (2) dissolving the product A in dichloromethane solvent, adding trifluoromethanesulfonic anhydride and pyridine in an ice-water bath, stirring and mixing thoroughly, and then stirring and reacting at room temperature for 14 hours, adding hexane to dilute the reaction system, separating the precipitate, washing, and drying to obtain product B; dissolving the product B in toluene solvent, adding pyridine, heating to 100°C and stirring and reacting for 14 hours, cooling after the reaction is completed, adding hexane to dilute the reaction system, separating the precipitate, washing, and drying to obtain product C; the mass ratio of the product A to the trifluoromethanesulfonic anhydride and the pyridine is 1:2:0.57; the mass ratio of the product B to the pyridine is 1:1.5;

[0071] (3) The product C is dissolved in a mixed solvent of dimethylformamide and ethylene glycol dimethyl ether, tetramethylguanidine is added, the temperature is raised to 100°C under a protective atmosphere and the mixture is stirred and reacted for 14 hours. After the reaction is completed, the mixture is cooled, concentrated under reduced pressure, and purified on a silica gel column. The mobile phase is a mixed solution of hexane and dichloromethane (v / v=1 / 9) to obtain product D; the product D is dissolved in tetrahydrofuran solvent, boron tribromide is added, the mixture is stirred and reacted for 4 hours under a protective atmosphere and room temperature. After the reaction is completed, 0.01 mol / L dilute hydrochloric acid and hexane (v / v=1 / 10) are added to dilute the reaction system, the precipitate is separated, washed, and dried to obtain the product; the mass ratio of the product C to the tetramethylguanidine is 1:11; the mass ratio of the product D to the boron tribromide is 1:0.46;

[0072] The silicone oil is polyether modified silicone oil, model H-204;

[0073] The catalyst is an organotin catalyst, model T-9 (stannous octoate);

[0074] The preparation method of the highly breathable sponge foam material is the same as that in Example 1.

[0075] Example 5

[0076] A highly breathable sponge foam material, comprising the following components in parts by weight:

[0077] 100 parts of modified polyisocyanate, 160 parts of polyol, 4 parts of deionized water, 2 parts of silicone oil, 1 part of catalyst;

[0078] The modified polyisocyanate is modified MDI-8019 (Wanhua);

[0079] The polyol is a mixture of polyether polyol and polymer polyol in a mass ratio of 2.4:1; the model of the polyether polyol is POLYOL-TP360; the model of the polymer polyol is POP-36 / 28;

[0080] The silicone oil is polyether modified silicone oil, model H-204;

[0081] The catalyst is an organotin catalyst, model T-9 (stannous octoate);

[0082] The preparation method of the highly breathable sponge foam material is the same as that in Example 1.

[0083] The highly breathable sponge foam materials prepared in Examples 1-5 were tested and compared in terms of performance. The tensile strength was measured according to GB / T 6344-2008, the rebound rate was measured according to GB / T 6670-2008, the tear strength was measured according to GB / T 10808-2006, and the air permeability was measured according to JIS K6400-1 7B method. The test results are shown in the following table:

[0084]

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A highly breathable sponge foam material, characterized in that: The composition is composed of the following components in parts by weight: 100 parts of modified polyisocyanate, 150-200 parts of polyol, 10-50 parts of first modified monomer, 4-18 parts of second modified monomer, 2-5 parts of foaming agent, 0.5-3 parts of silicone oil, 0.5-2 parts of catalyst; The preparation method of the first modified monomer comprises the following steps: (1) Weighing 1,4-diacetylpiperazine-2,5-dione and 3,5-diethoxybenzaldehyde respectively and dissolving them in dimethylformamide solvent, adding triethylamine, heating to 100-120°C and stirring to react for 12-20 hours, cooling after the reaction is completed, adding water to dilute the reaction system, separating the precipitate, washing, and drying to obtain product A; (2) dissolving the product A in dichloromethane solvent, adding trifluoromethanesulfonic anhydride and pyridine in an ice-water bath, stirring and mixing thoroughly, and then stirring and reacting at room temperature for 12-20 hours, adding hexane to dilute the reaction system, separating the precipitate, washing, and drying to obtain product B; dissolving the product B in toluene solvent, adding pyridine, heating to 100-120°C and stirring and reacting for 12-20 hours, cooling after the reaction is completed, adding hexane to dilute the reaction system, separating the precipitate, washing, and drying to obtain product C; (3) dissolving the product C in a mixed solvent of dimethylformamide and ethylene glycol dimethyl ether, adding tetramethylguanidine, heating to 100-120° C. under a protective atmosphere and stirring the mixture for 12-20 hours, cooling after completion of the reaction, concentrating under reduced pressure, and then purifying on a silica gel column to obtain product D; dissolving the product D in a tetrahydrofuran solvent, adding boron tribromide, stirring the mixture for 2-8 hours under a protective atmosphere and at room temperature, adding dilute hydrochloric acid and hexane to dilute the reaction system, separating the precipitate, washing, and drying the mixture; The second modified monomer is 2,7-dihydroxy-9-fluorenone.

2. A highly breathable sponge foam material according to claim 1, characterized in that: The modified polyisocyanate is one or more of modified MDI-8019, modified MDI-2412, and modified MDI-5412.

3. The highly breathable sponge foam material according to claim 1, characterized in that: The polyol is a mixture of polyether polyol and polymer polyol in a mass ratio of (2-3):1; the polyether polyol includes one or more of the models POLYOL-TP360, POLYOL-TP390, and POLYOL-TP440; the polymer polyol includes one or more of the models POP-36 / 28, POP-36 / 30, and POP-36 / 45.

4. The highly breathable sponge foam material according to claim 1, characterized in that: The mass ratio of the 1,4-diacetylpiperazine-2,5-dione, the 3,5-diethoxy-benzaldehyde and the triethylamine in step (1) is 10:(10-14):(20-30).

5. The highly breathable sponge foam material according to claim 1, characterized in that: In step (2), the mass ratio of the product A to the trifluoromethanesulfonic anhydride and the pyridine is 1:(1.8-2.4):(0.5-0.7); the mass ratio of the product B to the pyridine is 1:(1.2-2).

6. The highly breathable sponge foam material according to claim 1, characterized in that: In step (3), the mass ratio of the product C to the tetramethylguanidine is 1:(8-13); the mass ratio of the product D to the boron tribromide is 1:(0.4-0.6).

7. The highly breathable sponge foam material according to claim 1, characterized in that: The foaming agent is deionized water.

8. The highly breathable sponge foam material according to claim 1, characterized in that: The silicone oil is one or more of H-204, MSD-9103, MSD-9102, and OFX-0190.

9. The highly breathable sponge foam material according to claim 1, characterized in that: The catalyst is stannous octoate or dibutyltin dilaurate.

10. The method for preparing a highly breathable sponge foam material according to any one of claims 1 to 9, characterized in that: The following steps are involved: The polyol, the first modified monomer, the second modified monomer, the blowing agent and the silicone oil are weighed in proportion and added to a stirrer, stirred at room temperature until uniform, heated to 30-50°C, and the modified polyisocyanate and the catalyst are added and stirred at high speed, and then transferred to a preheated mold at a temperature of 50-70°C, kept warm for 5-10 minutes, formed in the mold for 5-10 minutes, and then demolded to obtain the highly breathable sponge foam material.

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