Preparation method of two-component polyurethane synthetic leather foamed by supercritical fluid

Abstract

The invention discloses a preparation method of two-component polyurethane synthetic leather by applying supercritical fluid foaming. The preparation method comprises the following steps: step (1), preparing waterborne polyurethane surface layer slurry; (2) preparing waterborne polyurethane intermediate layer slurry; step (3), preparing a double-component polyurethane bonding layer slurry; (4) coating the surface of release paper with the waterborne polyurethane surface layer slurry to obtain a waterborne polyurethane surface layer; (5) coating the waterborne polyurethane surface layer with the waterborne polyurethane intermediate layer slurry to obtain a waterborne polyurethane intermediate layer; (6) coating the waterborne polyurethane middle layer with the bi-component polyurethane bonding layer slurry, so as to obtain a bi-component polyurethane bonding layer; and (7) adhering the two-component polyurethane adhesive layer to the base cloth, and curing to obtain the synthetic leather. The size of foaming holes and the foaming ratio can be controlled through a supercritical fluid pressurization system, two components are mixed uniformly in a high-temperature and high-pressure system, the film forming leveling is better, and the synthetic leather is softer in hand feeling.

Description

Technical Field

[0001] The invention belongs to the technical field of synthetic leather production, and particularly relates to a method for preparing two-component polyurethane synthetic leather by using supercritical fluid foaming. Background Art

[0002] As a composite material, synthetic leather can be functionalized by adding various functional materials during the molding process. As a new technology product in the synthetic leather industry, water-based synthetic leather has many functions and processes to be developed.

[0003] Supercritical fluid microporous foaming generally uses CO2 or N2 as a physical foaming agent. CO2 and N2 have stable chemical properties, low prices, are non-toxic and harmless, and are environmentally friendly; the critical pressure and temperature of supercritical CO2 and N2 are relatively mild and easy to achieve, and have good solubility in polymers, strong diffusion ability, and are easy to control. They can be mixed and dissolved with a variety of coating components, and the solubility and viscosity can be changed by adjusting the temperature and pressure; SCF foaming technology can make the gas dispersed evenly and produce uniform fine-porous structure foam, which can significantly improve mechanical properties and low density. It has the benefit of carbon synergistic emission reduction, and can use carbon dioxide in industrial waste gas as raw material to reduce greenhouse gas emissions.

[0004] The traditional polyurethane rubber (PU) synthetic leather and polyvinyl chloride (PVC) artificial leather on the market are not breathable, not resistant to aging, not resistant to temperature, easy to hydrolyze, easy to stain, and the solvent-based ones use a lot of DMF, butanone, toluene and other harmful substances during the manufacturing and use process. Solvent-free polyurethane synthetic leather does not add other organic, inorganic solvents and other harmful substances during production, and is an environmentally friendly production.

[0005] Two-component solvent-free polyurethane synthetic leather has the advantages of strong leather feel and good durability, but its plastic feel and stiff feel have become important factors restricting its development and promotion. Summary of the invention

[0006] The invention provides a method for preparing two-component polyurethane synthetic leather by using supercritical fluid foaming. The size of foaming holes and the foaming ratio can be controlled by a supercritical fluid pressurizing system, and the two components are mixed evenly in a high-temperature and high-pressure system, so that the film formation and leveling are better and the synthetic leather feels softer.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a two-component polyurethane synthetic leather using supercritical fluid foaming comprises the following steps:

[0009] Step (1), preparing a waterborne polyurethane surface layer slurry: adding a leveling agent, a defoaming agent, a slip agent, a waterborne color paste, a thickener, and a cross-linking curing agent to an anionic aliphatic waterborne polyurethane, stirring evenly, filtering, and vacuum degassing to obtain the waterborne polyurethane surface layer slurry;

[0010] Step (2), preparing a waterborne polyurethane intermediate layer slurry: adding a leveling agent, a defoaming agent, a waterborne color paste, and a thickener to an anionic aliphatic waterborne polyurethane, stirring evenly, filtering, and vacuum degassing to obtain the waterborne polyurethane intermediate layer slurry;

[0011] Step (3), preparing a two-component polyurethane adhesive layer slurry: component A, filler, and catalyst are pre-stirred and mixed and then added to material tank A; component B is added to material tank B, and the liquid is gasified by decompression, cooled and pressurized, and then transported to material tank A in a predetermined ratio, and fully mixed with the components in material tank A under a supercritical state to obtain the two-component polyurethane adhesive layer slurry;

[0012] Step (4), applying the waterborne polyurethane surface layer slurry on the surface of the release paper, heating and drying, to obtain the waterborne polyurethane surface layer;

[0013] Step (5), applying the waterborne polyurethane intermediate layer slurry on the waterborne polyurethane surface layer, heating and drying, to obtain a waterborne polyurethane intermediate layer;

[0014] Step (6), applying the two-component polyurethane adhesive layer slurry on the waterborne polyurethane intermediate layer, heating and drying to the required laminating dryness and wetness, so as to obtain the two-component polyurethane adhesive layer;

[0015] Step (7), semi-dry laminating the two-component polyurethane adhesive layer to the base fabric, separating and rolling up after aging, so as to obtain synthetic leather.

[0016] In the above technical scheme, in step (1), the mass ratio of anionic aliphatic water-based polyurethane, leveling agent, defoaming agent, slip agent, water-based color paste, thickener, and cross-linking curing agent is 100: (0.01-1): (0.01-1): (0.1-1): (1-10): (0.1-5): (0.1-10).

[0017] In the above technical solution, in step (2), the mass ratio of anionic aliphatic waterborne polyurethane, leveling agent, defoaming agent, waterborne color paste and thickener is 100:(0.01-1):(0.01-1):(1-10):(0.1-5).

[0018] In the above technical solution, in step (3), the mass ratio of component A, component B, filler and catalyst is 100:(50-120):(0-30):(0.01-1).

[0019] In the above technical solution, in step (3), component A is a polyether polyol, and component B is an aromatic isocyanate.

[0020] In the above technical solution, in step (3), the filler is one or a mixture of two or more of matting powder, aluminum hydroxide, aluminum oxide, magnesium hydroxide, zinc borate, aluminum silicate, magnesium carbonate, glass microbeads, white carbon black, silicone resin powder, silicon dioxide, calcium carbonate or magnesium oxide.

[0021] The beneficial effects of the present invention are:

[0022] 1. The synergistic effect of supercritical fluid makes the solvent-free A / B material mixing more uniform, the fillers and additives in the A material are more evenly dispersed, and the evenly mixed homogeneous system is conducive to providing film-forming leveling.

[0023] 2. The supercritical carbon dioxide pressurization system can control the size of the foaming holes and the foaming ratio. The fluid flow rate, foaming temperature and pressure, depressurization rate and other processes can adjust the opening and closing of the foam cells, so that the two components are mixed evenly, the film leveling is better, and the synthetic leather feels softer. DETAILED DESCRIPTION

[0024] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. The present invention can be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that this disclosure will be thorough and complete, and the concept of the present invention will be fully conveyed to those skilled in the art, and the present invention will only be limited by the claims.

[0025] The present invention provides a method for preparing a two-component polyurethane synthetic leather using supercritical fluid foaming. The synthetic leather comprises a surface layer, an intermediate layer, an adhesive layer and a base fabric layer from top to bottom. The specific preparation method is as follows:

[0026] Step (1), preparing a waterborne polyurethane surface slurry: adding a leveling agent, a defoaming agent, a slip agent, a waterborne color paste, a thickener, and a cross-linking curing agent to an anionic aliphatic waterborne polyurethane, stirring evenly, filtering, and vacuum degassing to obtain a waterborne polyurethane surface slurry;

[0027] Among them, the mass ratio of anionic aliphatic water-based polyurethane, leveling agent, defoaming agent, slip agent, water-based color paste, thickener and cross-linking curing agent is 100: (0.01-1): (0.01-1): (0.1-1): (1-10): (0.1-5): (0.1-10).

[0028] The solid content of anionic aliphatic waterborne polyurethane is 30-40%.

[0029] The leveling agent is a silicone-modified polyether type water-based leveling agent, such as BYK's BYK-346 and BYK-348.

[0030] Defoaming agent is a silicone-modified anti-bubble agent, such as BYK's BYK-024 and BYK-054.

[0031] The slip agent is a silicone feel additive, such as JN3-018.

[0032] Water-based colorants are water-based colorants used in conventional synthetic leather production, such as Deep Blue Technology's colorant products.

[0033] The thickener is a thickener for water-based polyurethane, such as Wanhua's thickener U-605 (associative type).

[0034] The cross-linking curing agent is an aliphatic polyisocyanate water-based cross-linking curing agent, such as Covestro

[0035] Step (2), preparing a waterborne polyurethane intermediate layer slurry: adding a leveling agent, a defoaming agent, a waterborne color paste, and a thickener to an anionic aliphatic waterborne polyurethane, stirring evenly, filtering, and vacuum degassing to obtain a waterborne polyurethane intermediate layer slurry;

[0036] Among them, the mass ratio of anionic aliphatic water-based polyurethane, leveling agent, defoamer, water-based color paste and thickener is 100: (0.01-1): (0.01-1): (1-10): (0.1-5).

[0037] The solid content of anionic aliphatic waterborne polyurethane is 40-50%.

[0038] The leveling agent is a silicone-modified polyether type water-based leveling agent, such as BYK's BYK-346 and BYK-348.

[0039] Defoaming agent is a silicone-modified anti-bubble agent, such as BYK's BYK-024 and BYK-054.

[0040] Water-based colorants are water-based colorants used in conventional synthetic leather production, such as Deep Blue Technology's colorant products.

[0041] The thickener is a thickener for water-based polyurethane, such as Wanhua's thickener U-605 (associative type).

[0042] Step (3), preparing a two-component polyurethane adhesive layer slurry: component A, filler, and catalyst are pre-stirred and mixed and then added to material tank A; component B is added to material tank B, and the liquid is gasified by decompression, cooled and pressurized, and then transported to material tank A in a predetermined ratio, and fully mixed with the components in material tank A under a supercritical state, so as to obtain a two-component polyurethane adhesive layer slurry;

[0043] Among them, the mass ratio of component A, component B, filler and catalyst is 100:(50-120):(0-30):(0.01-1).

[0044] Component A is polyether polyol, and component B is aromatic isocyanate, such as Hexin Technology HX-NS-2003A / B, HX-NS-6006A / B, etc.

[0045] In the present invention, material A first cooperates with supercritical fluid to evenly disperse fillers and catalysts, and then material B is introduced for reaction, resulting in good leveling, sufficient mixing, and fast reaction. The process of fluid flow rate, pressure, etc. can adjust the cell opening and closing, and the synthetic leather has a softer feel.

[0046] The filler is one or a mixture of two or more of matting powder, aluminum hydroxide, aluminum oxide, magnesium hydroxide, zinc borate, aluminum silicate, magnesium carbonate, glass microbeads, white carbon black, organic silicone resin micropowder, silicon dioxide, calcium carbonate or magnesium oxide.

[0047] The catalyst is a metal or amine catalyst, such as HX-304, HX-513, HX-304, etc. produced by Hexin Technology.

[0048] Step (4), applying the waterborne polyurethane surface layer slurry on the surface of the release paper, heating and drying, to obtain the waterborne polyurethane surface layer;

[0049] Step (5), applying the waterborne polyurethane intermediate layer slurry on the waterborne polyurethane surface layer, heating and drying, to obtain the waterborne polyurethane intermediate layer;

[0050] Step (6), applying the two-component polyurethane adhesive layer slurry on the waterborne polyurethane intermediate layer, heating and drying to the desired laminating dryness and wetness, thereby obtaining the two-component polyurethane adhesive layer;

[0051] Step (7), semi-dry laminating the two-component polyurethane adhesive layer to the base fabric, separating and rolling up after ripening, and obtaining the synthetic leather.

[0052] Among them, resins with different solid contents are selected according to the grammage of the base fabric, and the base fabric can be non-woven fabric, woven fabric, knitted fabric, microfiber, etc.

[0053] After the synthetic leather was prepared by the preparation method of the present invention, performance tests were performed using the national standard and industry standard for synthetic leather. The test results are shown in Table 1.

[0054] Table 1 Experimental test results

[0055]

[0056] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing a two-component polyurethane synthetic leather using supercritical fluid foaming, characterized in that: The following steps are involved: Step (1), preparing a waterborne polyurethane surface layer slurry: adding a leveling agent, a defoaming agent, a slip agent, a waterborne color paste, a thickener, and a cross-linking curing agent to an anionic aliphatic waterborne polyurethane, stirring evenly, filtering, and vacuum degassing to obtain the waterborne polyurethane surface layer slurry; Step (2), preparing a waterborne polyurethane intermediate layer slurry: adding a leveling agent, a defoaming agent, a waterborne color paste, and a thickener to an anionic aliphatic waterborne polyurethane, stirring evenly, filtering, and vacuum degassing to obtain the waterborne polyurethane intermediate layer slurry; Step (3), preparing a two-component polyurethane adhesive layer slurry: component A, filler, and catalyst are pre-stirred and mixed and then added to material tank A; component B is added to material tank B, and the liquid is gasified by decompression, cooled and pressurized, and then transported to material tank A in a predetermined ratio, and fully mixed with the components in material tank A under a supercritical state to obtain the two-component polyurethane adhesive layer slurry; Step (4), applying the waterborne polyurethane surface layer slurry on the surface of the release paper, heating and drying, to obtain the waterborne polyurethane surface layer; Step (5), applying the waterborne polyurethane intermediate layer slurry on the waterborne polyurethane surface layer, heating and drying, to obtain a waterborne polyurethane intermediate layer; Step (6), applying the two-component polyurethane adhesive layer slurry on the waterborne polyurethane intermediate layer, heating and drying to the required laminating dryness and wetness, so as to obtain the two-component polyurethane adhesive layer; Step (7), semi-dry laminating the two-component polyurethane adhesive layer to the base fabric, separating and rolling up after aging, so as to obtain synthetic leather.

2. The preparation method according to claim 1, characterized in that: In step (1), the mass ratio of anionic aliphatic waterborne polyurethane, leveling agent, defoamer, slip agent, waterborne color paste, thickener and cross-linking curing agent is 100: (0.01-1): (0.01-1): (0.1-1): (1-10): (0.1-5): (0.1-10).

3. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of anionic aliphatic waterborne polyurethane, leveling agent, defoaming agent, waterborne color paste and thickener is 100:(0.01-1):(0.01-1):(1-10):(0.1-5).

4. The preparation method according to claim 1, characterized in that: In step (3), the mass ratio of component A, component B, filler and catalyst is 100:(50-120):(0-30):(0.01-1).

5. The preparation method according to claim 1, characterized in that: In step (3), component A is a polyether polyol, and component B is an aromatic isocyanate.

6. The preparation method according to claim 1, characterized in that: In step (3), the filler is one or a mixture of two or more of matting powder, aluminum hydroxide, aluminum oxide, magnesium hydroxide, zinc borate, aluminum silicate, magnesium carbonate, glass microbeads, white carbon black, silicone resin powder, silicon dioxide, calcium carbonate or magnesium oxide.

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