Thermoplastic polyurethane foam material for preparing cosmetic cotton and its preparation and application

Abstract

The present invention discloses a thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton, as well as its preparation method and application. The preparation method comprises the following steps: thermoplastic polyurethane A and thermoplastic polyurethane B are blended in a mass ratio of 1:2-19, and then put into a casting machine, and extrusion casting is performed to prepare a thermoplastic polyurethane sheet; the number average molecular weight of thermoplastic polyurethane A is 20,000-80,000 g / mol; the number average molecular weight of thermoplastic polyurethane B is 80,000-250,000 g / mol; the number average molecular weight of thermoplastic polyurethane A is lower than that of thermoplastic polyurethane B by more than 50,000 g / mol; the thermoplastic polyurethane sheet is placed in an autoclave or a high-pressure mold, a physical foaming agent is introduced, the autoclave or the high-pressure mold is heated and pressurized, then the pressure is released, and the temperature is cooled to obtain the thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton.

Description

Technical Field

[0001] The present invention relates to the technical field of thermoplastic polyurethane foam materials, and in particular to a thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton, and a preparation method and application thereof. Background Art

[0002] Cosmetic cotton pads are an essential cosmetic item in modern society, especially favored by modern women. The cosmetics industry is rapidly developing, and demand for cosmetic cotton pads is increasing, with an even greater need for high-quality cotton pads. Traditional nitrile rubber cotton pads have large pores, a rough feel, and poor skin-friendliness. Polyurethane cotton pads offer smaller pores, a smoother surface, and a smoother feel, making them the most popular material for cosmetic cotton pads.

[0003] In the prior art, polyurethane cosmetic cotton pads are foamed using polyols with two or more functional groups, water as a blowing agent, and low-boiling-point compounds such as chlorofluorocarbons, dichloromethane, and cyclopentane as auxiliary blowing agents. Furthermore, chain extenders, cell openers, foam levelers, emulsifiers, catalysts, and other substances are added. For example, patent CN113861370B discloses a polyurethane composite material for cosmetic cotton pads and its preparation method. The polyurethane composite material comprises component A and component B. Component A comprises silica lime, a blowing agent, a chain extender, emulsifying wax, a cell opener, and a color paste, while component B comprises two polyether polyols, a crosslinking polyether, and a catalyst. To prepare the cosmetic cotton pads, component A and component B are poured into a mold in a specific ratio, followed by foaming to produce the foam material for the cosmetic cotton pads.

[0004] Patent publication number CN 108503785 A discloses a polyurethane cosmetic cotton pad made from components A and B. Component A is composed of the following raw materials, by weight: 30-50 parts polyether polyol DDL-4000D; 50-70 parts polyether polyol POP45G; 2-4 parts water; 0.4-0.8 parts catalyst; 5-10 parts physical foaming agent; 0.5-2.5 parts foam stabilizer; and 1-2 parts sponge color paste. Component B is composed of the following raw materials, by weight: 25-40 parts isocyanate. Component B is added to the mixture of component A, stirred evenly, and then placed in a mold and cured for 12-24 hours to produce the polyurethane cosmetic cotton pad.

[0005] The polyurethane cosmetic cotton of the prior art, on the one hand, has a large amount of residual substances and odor due to the addition of a large number of additives; on the other hand, the mechanical properties and rebound properties of the polyurethane cosmetic cotton produced by this preparation process are generally deviated; in addition, the cosmetic cotton of the polyurethane material needs to produce a cross-linked structure when foaming, and the used cosmetic cotton or the scraps of the cosmetic cotton cannot be recycled. Summary of the Invention

[0006] In response to the above technical problems and the shortcomings in the art, the present invention provides a method for preparing a thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton pads. The prepared thermoplastic polyurethane foam material has a high open porosity, is easier to adhere to powder when used to prepare cosmetic cotton pads, and has the characteristics of low odor, fine pores, comfortable feel, no adverse effects on human skin, good rebound, excellent mechanical properties, and no cross-linking structure. The preparation method of the present invention is simple in process, does not require the addition of other chemical substances, and is environmentally friendly.

[0007] A method for preparing a thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton comprises the steps of:

[0008] (1) Thermoplastic polyurethane A and thermoplastic polyurethane B are blended in a mass ratio of 1:2-19 and then put into a casting machine, and extrusion casting is performed to prepare a thermoplastic polyurethane sheet;

[0009] The number average molecular weight of the thermoplastic polyurethane A is 20,000-80,000 g / mol;

[0010] The number average molecular weight of the thermoplastic polyurethane B is 80,000-250,000 g / mol;

[0011] The number average molecular weight of the thermoplastic polyurethane A is lower than the number average molecular weight of the thermoplastic polyurethane B by more than 50,000 g / mol;

[0012] (2) placing the thermoplastic polyurethane sheet in an autoclave or a high-pressure mold, introducing a physical foaming agent, heating and pressurizing the autoclave or the high-pressure mold, then releasing the pressure and cooling the mold to obtain the thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton.

[0013] Prior art polyurethane foam cosmetic cotton pads are usually non-thermoplastic, difficult to recycle and reuse, and have problems such as odor residue, poor mechanical properties and rebound performance. To this end, the present invention takes a different approach and proposes the use of thermoplastic polyurethane foam material as cosmetic cotton pads. However, in general, the closed-cell rate of thermoplastic polyurethane foam material is relatively high, which leads to its low powder absorption rate and the problem of difficulty in hanging powder. Based on this, the inventors have successfully solved the technical problem of low open-cell rate of thermoplastic polyurethane foam material after extensive research. At the same time, there is no odor residue and both mechanical properties and rebound performance are taken into account, making the thermoplastic polyurethane foam material of the present invention more suitable for use as cosmetic cotton pads.

[0014] In the present invention, the composition and type of thermoplastic polyurethane A and thermoplastic polyurethane B are not particularly limited. Thermoplastic polyurethane B, having a number average molecular weight of 80,000-250,000 g / mol, serves as a backbone to provide support. A specific amount of thermoplastic polyurethane A, having a number average molecular weight of 20,000-80,000 g / mol and at least 50,000 g / mol lower than that of thermoplastic polyurethane B, is introduced to form a thermoplastic polyurethane foam material having a relatively high open porosity by a process of casting followed by physical autoclave pressing or compression molding.

[0015] Thermoplastic polyurethane B has a high molecular weight and acts as a backbone, providing support and ensuring mechanical properties and strength, thereby enabling better foaming. Therefore, a sufficient amount of thermoplastic polyurethane B is required. The present invention requires that, based on the total mass of thermoplastic polyurethane A and thermoplastic polyurethane B being 100%, the mass of thermoplastic polyurethane B should account for no less than two-thirds. Otherwise, excessive amounts of thermoplastic polyurethane A will make foaming difficult.

[0016] On the other hand, the present invention requires that the molecular weight of thermoplastic polyurethane A is low and the difference in molecular weight with thermoplastic polyurethane B is sufficiently large. At the same time, it requires that the mass proportion of thermoplastic polyurethane A cannot be less than 5% (based on the total mass of thermoplastic polyurethane A and thermoplastic polyurethane B as 100%). Only when these conditions are met at the same time can a thermoplastic polyurethane foam material with a higher open porosity be obtained through the process of casting + physical autoclave pressing or molding foaming.

[0017] It should be noted that the two-component combination of thermoplastic polyurethane A and thermoplastic polyurethane B is an essential technical feature of the present invention. Using only one thermoplastic polyurethane alone, regardless of how its molecular weight is controlled, only a thermoplastic polyurethane foam with a high closed-cell ratio can be obtained. In other words, it is impossible to achieve the required open-cell ratio required by the present invention through a casting followed by physical autoclave or compression foaming process.

[0018] In order to make the thermoplastic polyurethane foam material have better skin-friendliness and comfortable flexibility after being made into cosmetic cotton, in step (1), the Shore hardness of the thermoplastic polyurethane B is preferably 40A-80A.

[0019] In step (1), the Shore hardness of the thermoplastic polyurethane A is preferably 40A-95A.

[0020] In step (1), the thickness of the thermoplastic polyurethane sheet may be 0.1-2 mm.

[0021] Preferably, in step (1), the extrusion casting temperature of the casting machine is set to 130-220°C.

[0022] In step (2), the physical foaming agent may be one or a mixture of nitrogen, carbon dioxide, butane, pentane, and pentafluoropropane.

[0023] Preferably, in step (2), the temperature of the autoclave or the high-pressure mold is raised to 80-150° C. and the pressure is raised to 3-20 MPa.

[0024] In step (2), if the pressure relief rate is too low, the open porosity of the thermoplastic polyurethane foam material will decrease, and the performance of the prepared cosmetic cotton in adhering cosmetic powder will deteriorate. Preferably, in step (2), the pressure relief rate is not less than 2 MPa / s.

[0025] The present invention also provides a thermoplastic polyurethane foam material prepared by the preparation method and can be used to prepare cosmetic cotton.

[0026] Preferably, the open porosity of the thermoplastic polyurethane foam material is not less than 8%. The open porosity is tested using an HX-TP polyurethane rigid foam open and closed porosity tester. The specific principle is: using the Archimedean principle - gas expansion displacement method, using a small molecule inert gas (He or N2) as the medium, and calculating the volume of gas displaced by the sample in the test chamber using the ideal gas state equation: PV = nRT, thereby accurately measuring the true volume of the sample (including closed pores). The open and closed porosity can then be calculated based on the material's apparent volume and the volume before foaming.

[0027] The present invention also provides the use of the thermoplastic polyurethane foam material in preparing cosmetic cotton.

[0028] As a general inventive concept, the present invention also provides a cosmetic cotton pad prepared from the thermoplastic polyurethane foam material.

[0029] The present invention further provides a method for preparing cosmetic cotton, wherein the thermoplastic polyurethane foam material is cut to obtain cosmetic cotton.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention adopts thermoplastic polyurethane foam material to prepare cosmetic cotton. The foam material is foamed by pure physical gas. The prepared cosmetic cotton has no cross-linked structure and can be recycled repeatedly.

[0032] 2. The addition of thermoplastic polyurethane A with a low number-average molecular weight (20,000-80,000 g / mol and at least 50,000 g / mol lower than the base thermoplastic polyurethane B) and rapid pressure relief during foaming give the thermoplastic polyurethane foam a certain open porosity, allowing it to better adhere to cosmetic powder when used as a cosmetic cotton pad. Furthermore, the present invention utilizes a purely physical foaming method, resulting in a thermoplastic polyurethane foam with low odor, fine pores, good resilience, and excellent mechanical properties.

[0033] 3. The present invention discloses a preparation method of a thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton. Compared with the traditional cosmetic cotton production process, the preparation method of the present invention is simple, does not require the addition of other chemical substances, and is environmentally friendly.

[0034] 4. The present invention discloses the application of thermoplastic polyurethane foam material in the preparation of cosmetic cotton. The prepared cosmetic cotton has the properties of low odor, comfortable hand feel and no adverse effects on human skin. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention and are not intended to limit the scope of the invention. The operating methods in the following examples where no specific conditions are specified are generally performed under conventional conditions or as recommended by the manufacturer.

[0036] Note: The amount of foaming agent added during foaming is always excessive, and the foaming pressure setting requirement is controlled by exhausting the air during the process.

[0037] Example 1

[0038] (1) 10 kg of thermoplastic polyurethane A with a Shore hardness of 60A and a number average molecular weight of 60,000 g / mol and 90 kg of thermoplastic polyurethane B with a Shore hardness of 55A and a number average molecular weight of 120,000 g / mol were blended in a mixer and then put into a casting machine at a temperature of 150-170°C to prepare a sheet of thermoplastic polyurethane C by extrusion casting. The sheet thickness was 1 mm.

[0039] (2) The thermoplastic polyurethane C sheet prepared in step (1) was cut into a size of 30 cm × 30 cm, placed in a high-pressure mold, and introduced into a mixture of carbon dioxide and nitrogen at a mass ratio of 10:1. The temperature was raised to 110° C., the pressure was maintained at 10 MPa, and the pressure was rapidly released at a rate of 4 MPa / s to obtain a thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton pads. The prepared thermoplastic polyurethane foam material was placed at room temperature for 24 hours, and its performance was evaluated, as shown in the data in Table 1.

[0040] Example 2

[0041] (1) 10 kg of thermoplastic polyurethane A with a Shore hardness of 50A and a number average molecular weight of 30,000 g / mol and 40 kg of thermoplastic polyurethane B with a Shore hardness of 65A and a number average molecular weight of 100,000 g / mol were blended in a mixer and then put into a casting machine at a temperature of 170-180°C to prepare a sheet of thermoplastic polyurethane C by extrusion casting. The sheet thickness was 0.5 mm.

[0042] (2) The thermoplastic polyurethane C sheet in step (1) was cut into a size of 30 cm × 30 cm, placed in a high-pressure mold, and introduced into a mixture of carbon dioxide and nitrogen at a mass ratio of 10:2. The temperature was raised to 120° C., the pressure was maintained at 15 MPa, and finally the pressure was rapidly released at a rate of 5 MPa / s to obtain a thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton. The prepared thermoplastic polyurethane foam material was placed at room temperature for 24 hours, and its performance was evaluated, as shown in the data in Table 1.

[0043] Example 3

[0044] (1) 10 kg of thermoplastic polyurethane A with a Shore hardness of 40A and a number average molecular weight of 80,000 g / mol and 20 kg of thermoplastic polyurethane B with a Shore hardness of 80A and a number average molecular weight of 250,000 g / mol were blended in a mixer and then put into a casting machine at a temperature of 200-220°C to prepare a sheet of thermoplastic polyurethane C by extrusion casting. The sheet thickness was 0.1 mm.

[0045] (2) The thermoplastic polyurethane C sheet prepared in step (1) was cut into a size of 30 cm × 30 cm, placed in an autoclave, introduced with butane, heated to 140° C., maintained at a pressure of 3.5 MPa, and finally rapidly released the pressure at a rate of 2 MPa / s to obtain a thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton pads. The prepared thermoplastic polyurethane foam material was left at room temperature for 24 hours, and its performance was evaluated, as shown in Table 1.

[0046] Example 4

[0047] (1) 10 kg of thermoplastic polyurethane A with a Shore hardness of 95A and a number average molecular weight of 20,000 g / mol and 190 kg of thermoplastic polyurethane B with a Shore hardness of 40A and a number average molecular weight of 80,000 g / mol were blended in a mixer and then put into a casting machine at a temperature of 130-150° C. to prepare a sheet of thermoplastic polyurethane C by extrusion casting. The sheet thickness was 2 mm.

[0048] (2) The sheet of thermoplastic polyurethane C prepared in step (1) was cut into a size of 30 cm × 30 cm, placed in a high-pressure mold, and introduced into a mixture of carbon dioxide and nitrogen at a mass ratio of 10:5. The temperature was raised to 100° C., the pressure was maintained at 20 MPa, and the pressure was rapidly released at a rate of 3 MPa / s to obtain a thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton pads. The prepared thermoplastic polyurethane foam material was placed at room temperature for 24 hours, and its performance was evaluated, as shown in the data in Table 1.

[0049] Example 5

[0050] (1) 10 kg of thermoplastic polyurethane A with a Shore hardness of 70A and a number average molecular weight of 70,000 g / mol and 75 kg of thermoplastic polyurethane B with a Shore hardness of 60A and a number average molecular weight of 180,000 g / mol were blended in a mixer and then put into a casting machine at a temperature of 160-180°C to prepare a sheet of thermoplastic polyurethane C by extrusion casting. The sheet thickness was 1 mm.

[0051] (2) The thermoplastic polyurethane C sheet in step (1) was cut into a size of 30 cm × 30 cm, placed in a high-pressure mold, and introduced into a mixture of carbon dioxide and nitrogen with a mass ratio of 10:5. The temperature was raised to 115° C., the pressure was maintained at 12 MPa, and finally the pressure was rapidly released at a rate of 6 MPa / s to obtain a thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton. The prepared thermoplastic polyurethane foam material was placed at room temperature for 24 hours, and its performance was evaluated, as shown in the data in Table 1.

[0052] Comparative Example 1

[0053] Compared with Example 1, in Comparative Example 1, thermoplastic polyurethane A with a low number average molecular weight is not added, and thermoplastic polyurethane B is used entirely. The specific steps are as follows:

[0054] (1) 100 kg of thermoplastic polyurethane B with a Shore hardness of 55A and a number average molecular weight of 120,000 g / mol was put into a casting machine at a temperature of 150-170° C. and extruded to prepare a thermoplastic polyurethane sheet with a thickness of 1 mm.

[0055] (2) The thermoplastic polyurethane sheet prepared in step (1) was cut into a size of 30 cm × 30 cm and placed in a high-pressure mold. A mixture of carbon dioxide and nitrogen at a mass ratio of 10:1 was introduced. The temperature was raised to 110° C., the pressure was maintained at 10 MPa, and the pressure was rapidly released at a rate of 4 MPa / s to obtain a thermoplastic polyurethane foam material. The prepared thermoplastic polyurethane foam material was left at room temperature for 24 hours, and its performance was evaluated, as shown in Table 1.

[0056] Comparative Example 2

[0057] Compared with Example 1, in Comparative Example 2, the selected thermoplastic polyurethane A has a number average molecular weight 20,000 g / mol lower than that of the thermoplastic polyurethane B. The specific steps are as follows:

[0058] (1) 10 kg of thermoplastic polyurethane A with a Shore hardness of 60A and a number average molecular weight of 100,000 g / mol and 90 kg of thermoplastic polyurethane B with a Shore hardness of 55A and a number average molecular weight of 120,000 g / mol were blended in a mixer and then put into a casting machine at a temperature of 150-170°C to prepare a sheet of thermoplastic polyurethane C by extrusion casting. The sheet thickness was 1 mm.

[0059] (2) The thermoplastic polyurethane C sheet prepared in step (1) was cut into a size of 30 cm × 30 cm and placed in a high-pressure mold. A mixture of carbon dioxide and nitrogen at a mass ratio of 10:1 was introduced. The temperature was raised to 110° C., the pressure was maintained at 10 MPa, and the pressure was rapidly released at a rate of 4 MPa / s to obtain a thermoplastic polyurethane foam material. The prepared thermoplastic polyurethane foam material was left at room temperature for 24 hours, and its properties were evaluated, as shown in Table 1.

[0060] Table 1

[0061]

[0062] Note: Biocompatibility tests include skin irritation, cytotoxicity and allergy tests.

[0063] As shown in Table 1, compared to existing non-thermoplastic polyurethane foam cosmetic cotton pads, the thermoplastic polyurethane foam material for cosmetic cotton pads prepared in the present invention exhibits fine pores, good resilience, excellent mechanical properties, and no adverse effects on human skin. Furthermore, compared with Comparative Examples 1 and 2, the thermoplastic polyurethane foam material for cosmetic cotton pads in Example 1 exhibits a higher open cell ratio, which helps it adhere to more cosmetic powder when used as a cosmetic cotton pad. Finally, the preparation method of the present invention is simple, requires no additional chemical substances, and is environmentally friendly.

[0064] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing a thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton, characterized in that: Including steps: (1) Thermoplastic polyurethane A and thermoplastic polyurethane B are blended in a mass ratio of 1:2-19 and then put into a casting machine, and extrusion casting is performed to prepare a thermoplastic polyurethane sheet; The number average molecular weight of the thermoplastic polyurethane A is 20,000-80,000 g / mol; The number average molecular weight of the thermoplastic polyurethane B is 80,000-250,000 g / mol; The number average molecular weight of the thermoplastic polyurethane A is lower than the number average molecular weight of the thermoplastic polyurethane B by more than 50,000 g / mol; (2) placing the thermoplastic polyurethane sheet in an autoclave or a high-pressure mold, introducing a physical foaming agent, heating and pressurizing the autoclave or the high-pressure mold, then releasing the pressure, and cooling to obtain the thermoplastic polyurethane foam material that can be used to prepare cosmetic cotton; the pressure release rate is not less than 2 MPa / s; and the open porosity of the thermoplastic polyurethane foam material is not less than 8%.

2. The preparation method according to claim 1, characterized in that In step (1): The Shore hardness of the thermoplastic polyurethane A is 40A-95A; The Shore hardness of the thermoplastic polyurethane B is 40A-80A.

3. The preparation method according to claim 1, characterized in that In step (1), the thickness of the thermoplastic polyurethane sheet is 0.1-2 mm.

4. The preparation method according to claim 1, characterized in that In step (1), the temperature of the extrusion casting machine is set to 130-220°C.

5. The preparation method according to claim 1, characterized in that In step (2), the physical foaming agent is one or a mixture of nitrogen, carbon dioxide, butane, pentane, and pentafluoropropane.

6. The preparation method according to claim 1, characterized in that In step (2), the temperature of the autoclave or the high-pressure mold is raised to 80-150° C. and the pressure is raised to 3-20 MPa.

7. The thermoplastic polyurethane foam material prepared by the preparation method according to any one of claims 1 to 6 and can be used to prepare cosmetic cotton.

8. Use of the thermoplastic polyurethane foam material according to claim 7 in the preparation of cosmetic cotton.

9. A cosmetic cotton pad, characterized in that: Prepared from the thermoplastic polyurethane foam material described in claim 7.

10. A method for preparing cosmetic cotton, characterized in that: The thermoplastic polyurethane foam material according to claim 7 is cut to obtain a cosmetic cotton pad.

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