A wet foaming material for resistant leather and resistant leather prepared by the same

Abstract

The invention discloses a wet foaming material for leather resistance and leather resistance prepared therefrom, comprising a solvent, a polyurethane resin, and a water-soluble bio-based powder; the water-soluble bio-based powder is one or more of cyclodextrin, English gum, white dextrin, maltodextrin, and yellow dextrin. In the invention, the foaming material is mainly used for the bass layer in synthetic leather, which is mainly a mixture of a solvent, a polyurethane resin, and a soluble bio-based powder. The soluble bio-based powder can absorb water and dissolve. During the dissolution process, there will be a long swelling process, and then the swelling will be followed by dissolution. When swelling, it will expand, thereby forming pores inside the polyurethane resin. When the swelling limit is reached, dissolution will occur, thereby dissolving in the solvent, thereby leaving the pores inside the polyurethane. Therefore, when the soluble bio-based powder is used as the foaming material, it will not remain inside the polyurethane.

Description

Technical Field

[0001] The invention relates to the field of leather, and more particularly to a wet foaming material for leather resistant to brittle leather. Background Art

[0002] Genuine leather is an animal skin that has been depilated, tanned and chemically processed to be denatured and non-perishable. Due to the scarcity of genuine leather resources and the comfort and fashion of genuine leather, people have a special liking for genuine leather products. However, genuine leather is rare, so imitation leather came into being. Existing imitation leather includes recycled leather, microfiber leather and polyurethane synthetic leather.

[0003] In recent years, a kind of protein soft synthetic leather has appeared on the market. Wood powder, polyurethane resin solvent liquid, dimethylformamide, a small amount of polyvinyl alcohol powder, a small amount of pregelatinized starch and other raw materials are stirred to prepare wet foaming materials. Wood powder expands when it meets solvent, and the expanded wood powder, polyvinyl alcohol powder and pregelatinized starch are evenly dispersed in the mixture; the mixture is scraped on the base cloth, and the polyvinyl alcohol powder and pregelatinized starch in the coating expand when they meet water molecules. The pregelatinized starch granules swell to 50-100 times the original volume. The polyvinyl alcohol powder absorbs water equivalent to more than 7 times its own weight. The expanded polyvinyl alcohol powder and the expanded pregelatinized starch are washed out in hot water. The foaming layer shrinks during the drying process, and the polyvinyl alcohol powder and pregelatinized starch form large bubbles, and the wood powder forms small bubbles. It is a structure with large bubbles sandwiched between dense small bubbles. Polyvinyl alcohol is too viscous after swelling and solidification in water, and pregelatinized starch is even more viscous after swelling and solidification in water. It dissolves in water very slowly. In the solidification process of the solidification tank, wood powder must be used to transfer water to achieve the exchange of solvent and water. In the washing process of the washing tank, hot water is needed to accelerate the dissolution rate, and a lot of wood powder is needed to transfer water to achieve the purpose of cleaning. The polyvinyl alcohol washed out by water causes the dimethylformamide recovery system to be blocked. It is quite troublesome to clean the blockage, and it is necessary to modify the solvent recovery tower and other equipment. At present, there is only one manufacturer of this kind of protein-soft synthetic leather. The World Health Organization's International Agency for Research on Cancer has included industrial-grade polyvinyl alcohol in the list of Class 3 carcinogens. The recycled industrial-grade polyvinyl alcohol needs to be recycled by professional environmental protection qualified recycling units, which greatly increases the manufacturing cost.

[0004] The production capacity of this protein-like soft synthetic leather is limited and far from meeting the market demand. Its softness is proportional to the amount of wood powder, pulp powder, polyvinyl alcohol, and pregelatinized starch used. Therefore, the softer the protein-like soft leather is, the shorter its firmness and service life will be. The main advantage of protein-like soft synthetic leather is that it has a good soft effect, but the wet foaming layer with large pores feels loose, empty, and light, and does not have the fleshy feel and drape of sheep leather. Its leather grain is loose and wrinkled, and it is not beautiful. Softness and beauty cannot be taken into account at the same time. The same is true for sheepskin in terms of softness and beauty. If the leather grain is tight and beautiful, it will feel harder. If the leather grain is soft, it will be loose and wrinkled, and it will be unsightly. In order to pursue the feel, the softer it is, the worse its mechanical properties will be.

[0005] At present, PU synthetic leather all relies on wood powder to realize the production of base. Due to the presence of wood powder, base is prone to mold and corruption, affecting hygiene and quality. Genuine leather is more prone to mold and corruption due to its collagen tissue structure, which seriously affects hygiene and quality. Summary of the invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a wet foaming material that has both softness and mechanical properties and will not breed mold and corruption.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A wet foaming material for skin resistance.

[0009] include

[0010] Solvents, polyurethane resins, water-soluble bio-based powders;

[0011] The water-soluble bio-based powder is composed of one or more of modified starch, cyclodextrin, English gum, white dextrin, maltodextrin and yellow dextrin.

[0012] As a further improvement of the present invention,

[0013] The water-soluble bio-based powder absorbs 50% to 200% of its own weight of water to swell, and absorbs more than 100% to 400% of its own weight of water to dissolve.

[0014] As a further improvement of the present invention,

[0015] The solvent is dimethylformamide.

[0016] As a further improvement of the present invention,

[0017] The wet foaming material also includes a wax emulsion.

[0018] As a further improvement of the present invention,

[0019] The wax emulsion is one or more of paraffin wax emulsion, palm wax emulsion and PE wax emulsion.

[0020] As a further improvement of the present invention,

[0021] The wet foaming material further comprises silicone.

[0022] As a further improvement of the present invention,

[0023] The organic silicon is long-chain amino polyether block silicone oil or long-chain amino polyether block silicone oil emulsion.

[0024] As a further improvement of the present invention,

[0025] The mass ratio of the polyurethane resin to the water-soluble bio-based powder is 20-40:30-150.

[0026] As a further improvement of the present invention,

[0027] It also includes 2 to 15 parts of oil emulsion.

[0028] As another object of the present invention, a kind of resistant skin is provided,

[0029] It comprises a textured pavement layer and a wet foaming layer, and is characterized in that the wet foaming layer is made of the wet foaming material.

[0030] As a further improvement of the present invention,

[0031] It also includes a base fabric layer, on which the wet foaming layer is located, and the elastic stretch rate of the base fabric is less than 10%.

[0032] The beneficial effects of the present invention are as follows: in the present invention, the foaming material mainly used in the base layer of synthetic leather is mainly a mixture of solvent, polyurethane resin and soluble bio-based powder. The soluble bio-based powder can absorb water and dissolve. During the dissolution process, there will be a long swelling process, and then dissolve again. When swelling, it will expand, thereby forming pores inside the polyurethane resin. When the swelling limit is reached, it will dissolve, thereby dissolving in the solvent, thereby leaving the pores inside the polyurethane. Therefore, when the soluble bio-based powder is used as the foaming material, it will not remain inside the polyurethane.

[0033] Unlike wood powder fillers, after expanding as a foaming agent, it will remain inside the bass, and will constantly rub polyurethane during the continuous bending process, thereby reducing the mechanical properties of the bass. Wood powder is prone to mildew and decay, thereby reducing the weather resistance of the bass. Wood powder remains inside the bass. After being grabbed or wrinkled and pressed, it is difficult for the wood powder to return to its original state after being deformed by force, leaving scratches and pressure marks that affect the appearance, and it is impossible to produce high-end leather, especially leather with very fine leather grain. At present, sheepskin with very fine leather grain will also leave scratches and pressure marks after being grabbed or wrinkled and pressed, which affects the appearance. Therefore, the leather industry will not produce leather with very fine leather grain. The finer the leather grain, the more beautiful it is, and the finer the leather grain, the higher-end it is, but it is mainly difficult to produce.

[0034] The purpose is to no longer use wood powder as foaming filler and reduce the use of wood as foaming filler, thereby improving the mechanical properties, softness and weather resistance of the bass, improving the bass's ability to recover after deformation due to force, and increasing the possibility of producing leather with very fine leather grain.

[0035] In the selection of soluble bio-based powder, the present invention selects modified starch, cyclodextrin, English gum, white dextrin, maltodextrin, and yellow dextrin. The soluble bio-based powder selected by the present invention can be evenly dispersed in the mixture, the wet foaming material is coated on the base cloth and then immersed in the coagulation liquid, the water molecules penetrate into each dextrin powder through DMF, the soluble bio-based powder quickly swells and gelatinizes after encountering water molecules, the soluble bio-based powder and the adjacent parts of the soluble bio-based powder expand and connect with each other during the swelling process, and the swollen soluble bio-based powders are irregularly connected in series with each other; while the soluble bio-based powder expands, the polyurethane resin slowly solidifies when encountering water molecules; after the soluble bio-based powder swells, it continues to dissolve into a dextrin aqueous solution when encountering infiltration water, the soluble bio-based powder aqueous solution and dimethylformamide are cleaned by water in the water washing process, and a foaming layer is obtained by drying, and a special foaming layer with a loofah-like structure is obtained. There is no need to use hot water for washing as in the prior art, or even to add other auxiliary substances for washing.

[0036] Compared with the prior art, the soluble bio-based powder used in the present invention has the ability to dissolve after swelling, and can form relatively uniform and dense bubbles. The synthetic leather produced will not be light, so calcium powder is not needed to increase the weight, but it can have good mechanical properties and weather resistance.

[0037] In the selection of soluble bio-based powders, the preferred performance is to absorb 50% to 200% of its own weight of water to swell, and absorb more than 100% to 400% of its own weight of water to dissolve. The pores formed in this way are relatively dense.

[0038] As a preferred embodiment of the present invention, a proper amount of wax emulsion is added, and the lubrication and astringency of the wax slow down the rebound speed of the foaming layer, making the rebound feel of the resistant leather close to or exceeding that of sheepskin.

[0039] In order to achieve moisture and oiliness, a grease emulsion is added to the wet foaming material. The emulsion plays a role in enhancing the uniform dispersion of powder particles in the wet foaming material, wetting the inner wall of the oil-slip pores to reduce friction, slow down the rebound speed and moisture absorption and weight gain.

[0040] Long-chain amino polyether block silicone oil or long-chain amino polyether block silicone oil emulsion is added to the above wet foaming material. Silicone plays a role in uniformly dispersing powder particles in the wet foaming material, reducing the friction between molecules and within the pores, and reducing the softness of the produced foaming layer. In the water washing process, long-chain amino polyether block silicone oil or long-chain amino polyether block silicone oil emulsion is more difficult to be washed out by water than short-chain amino polyether block silicone oil or short-chain amino polyether block silicone oil emulsion, and the softening effect is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is an electron microscope image of Example 1 of the present invention;

[0042] Figure 2 This is an electron microscope image of the second embodiment of the present invention;

[0043] Figure 3 This is an electron microscope image of comparative example 1 of the present invention;

[0044] Figure 4 This is an electron microscope image of comparative example 2 of the present invention. DETAILED DESCRIPTION

[0045] The present invention will be further described below in detail with reference to the embodiments shown in the accompanying drawings. Embodiment 1

[0046] Step 1: Preparation of wet foaming materials

[0047] Take weight parts:

[0048] 100 parts of polyurethane resin with a solid content of 30% and a modulus of 10 kgf / cm2

[0049] Yellow dextrin powder: 80 parts

[0050] DMF: 180 parts;

[0051] Take a proper amount of DMF and mix it with the polyurethane resin so that the viscosity of the wet foaming material is about 5000cps, which is a suitable coating viscosity.

[0052] The yellow dextrin powder has been tested and it has been found that 1 part of yellow dextrin can absorb 1 part of water by weight during the swelling stage and can dissolve after absorbing 2 parts of water.

[0053] Mixing yellow dextrin powder and remaining DMF to prepare a yellow dextrin mixture;

[0054] The polyurethane resin mixture and the yellow dextrin powder mixture are fully stirred and mixed to obtain a wet foaming material.

[0055] Step 2: Base fabric pretreatment

[0056] The base fabric with a thickness of 0.20 mm was immersed in a DMF aqueous solution with a concentration of 17%, the excess aqueous solution was pressed out with a squeeze roller, and the base fabric was ironed with an ironing wheel, and the humidity was 40%.

[0057] Step 3: Coating and solidification

[0058] The wet foaming material is evenly coated on the pretreated base cloth with a coating gap of 1.00 mm, and then immersed in a coagulation tank with a DMF aqueous solution with a concentration of 20% for coagulation, and the coagulation time is 20 minutes.

[0059] Step 4:

[0060] After complete solidification, it passes through the squeezing roller to squeeze out the excess solidifying liquid, and then is washed with clean water in a washing tank. The first section of the washing tank is washed with five groups of squeezing rollers, and the second section is washed with six groups of squeezing rollers. Finally, it is dried, expanded, and shaped to obtain a wet foaming layer. Embodiment 2

[0061] Step 1: Preparation of wet foaming materials

[0062] Take weight parts:

[0063] 100 parts of polyurethane resin with a solid content of 30% and a modulus of 10 kgf / cm2

[0064] Cyclodextrin: 80 parts

[0065] DMF: 180 parts;

[0066] Take an appropriate amount of DMF by weight to make the viscosity of the wet foaming material reach a suitable coating viscosity of about 5000 cps.

[0067] Cyclodextrin powder has been tested and found to absorb 2 parts by weight of water during the swelling phase and to be soluble after absorbing 3 parts of water.

[0068] Mixing cyclodextrin and remaining DMF to prepare a cyclodextrin mixture;

[0069] The polyurethane resin mixture and the cyclodextrin mixture are fully stirred and mixed to obtain a wet foaming material.

[0070] Step 2: Base fabric pretreatment

[0071] The base fabric with a thickness of 0.20 mm was immersed in a DMF aqueous solution with a concentration of 17%, the excess aqueous solution was pressed out with a squeeze roller, and the base fabric was ironed with an ironing wheel, and the humidity was 40%.

[0072] Step 3: Coating and solidification

[0073] The wet foaming material is evenly coated on the pretreated base cloth with a coating gap of 1.00 mm, and then immersed in a coagulation tank with a DMF aqueous solution with a concentration of 20% for coagulation, and the coagulation time is 20 minutes.

[0074] Step 4:

[0075] After complete solidification, it passes through the squeezing roller to squeeze out the excess solidifying liquid, and then is washed with clean water in a washing tank. The first section of the washing tank is washed with five groups of squeezing rollers, and the second section is washed with six groups of squeezing rollers. Finally, it is dried, expanded, and shaped to obtain a wet foaming layer. Embodiment 3

[0076] Step 1: Preparation of wet foaming materials

[0077] Take weight parts:

[0078] 100 parts of polyurethane resin with a solid content of 30% and a modulus of 10 kgf / cm2

[0079] Yellow dextrin powder: 80 parts

[0080] PE wax emulsion: 2 parts

[0081] Long-chain amino polyether block silicone oil emulsion: 10 parts

[0082] DMF: 180 parts;

[0083] Take an appropriate amount of DMF by weight to make the viscosity of the wet foaming material reach a suitable coating viscosity of about 5000 cps.

[0084] The yellow dextrin powder has been tested and it has been found that 1 part of yellow dextrin can absorb 1 part of water by weight during the swelling stage and can dissolve after absorbing 2 parts of water.

[0085] Mixing yellow dextrin powder and remaining DMF to prepare a yellow dextrin mixture;

[0086] The polyurethane resin mixture, the yellow dextrin powder mixture and other auxiliary materials are fully stirred and mixed to obtain a wet foaming material.

[0087] Step 2: Base fabric pretreatment

[0088] The base fabric with a thickness of 0.20 mm was immersed in a DMF aqueous solution with a concentration of 17%, the excess aqueous solution was pressed out with a squeeze roller, and the base fabric was ironed with an ironing wheel, and the humidity was 40%.

[0089] Step 3: Coating and solidification

[0090] The wet foaming material is evenly coated on the pretreated base cloth with a coating gap of 1.00 mm, and then immersed in a coagulation tank with a DMF aqueous solution with a concentration of 20% for coagulation, and the coagulation time is 20 minutes.

[0091] Step 4:

[0092] After complete solidification, it passes through the squeezing roller to squeeze out the excess solidifying liquid, and then is washed with clean water in a washing tank. The first section of the washing tank is washed with five groups of squeezing rollers, and the second section is washed with six groups of squeezing rollers. Finally, it is dried, expanded, and shaped to obtain a wet foaming layer. Embodiment 4

[0093] Step 1: Preparation of wet foaming materials

[0094] Take weight parts:

[0095] 100 parts of polyurethane resin with a solid content of 30% and a modulus of 10 kgf / cm2

[0096] Yellow dextrin powder: 80 parts

[0097] Grease emulsion: 5 parts

[0098] DMF: 180 parts;

[0099] Take an appropriate amount of DMF by weight to make the viscosity of the wet foaming material reach a suitable coating viscosity of about 5000 cps.

[0100] The yellow dextrin powder has been tested and it has been found that 1 part of yellow dextrin can absorb 1 part of water by weight during the swelling stage and can dissolve after absorbing 2 parts of water.

[0101] Mixing yellow dextrin powder and remaining DMF to prepare a yellow dextrin mixture;

[0102] The polyurethane resin mixture, the yellow dextrin powder mixture and other auxiliary materials are fully stirred and mixed to obtain a wet foaming material.

[0103] Step 2: Base fabric pretreatment

[0104] The base fabric with a thickness of 0.20 mm was immersed in a DMF aqueous solution with a concentration of 17%, the excess aqueous solution was pressed out with a squeeze roller, and the base fabric was ironed with an ironing wheel, and the humidity was 40%.

[0105] Step 3: Coating and solidification

[0106] The wet foaming material is evenly coated on the pretreated base cloth with a coating gap of 1.00 mm, and then immersed in a coagulation tank with a DMF aqueous solution with a concentration of 20% for coagulation, and the coagulation time is 20 minutes.

[0107] Step 4:

[0108] After complete solidification, it passes through the squeezing roller to squeeze out the excess solidifying liquid, and then is washed with clean water in a washing tank. The first section of the washing tank is washed with five groups of squeezing rollers, and the second section is washed with six groups of squeezing rollers. Finally, it is dried, expanded, and shaped to obtain a wet foaming layer.

[0109] Example 5: Preparation of resistant skin

[0110] Step 1: Get

[0111] 40 parts of dry polyurethane resin with a solid content of 30% and a modulus of 50 kgf / cm2

[0112] DMF: 50 parts

[0113] Butanone: 20 parts

[0114] A dry mixed solution is obtained;

[0115] Step 2: Preparation of release paper coating: Select the finest sheepskin-grained special release paper, apply the mixed liquid on the release paper film by dry method, with a coating gap of 0.20mm, and dry in an 80℃ oven for 20 minutes to obtain the release paper coating.

[0116] Step 3: Dry veneer:

[0117] The wet foaming layer obtained in Example 1, Example 2, Example 3, and Example 4 is directly laminated on the release paper coating obtained in step 2 by pressure, and then dried in an oven at 120°C for 30 minutes. After cooling with a cooling roller, the release paper and the wet foaming layer with laminated surfaces are rolled up separately to obtain finished leather.

[0118] Comparative Example 1:

[0119] Step 1: Preparation of wet foaming materials

[0120] Take weight parts:

[0121] 100 parts of polyurethane resin with a solid content of 30% and a modulus of 10 kgf / cm2

[0122] Pregelatinized starch: 50 parts

[0123] Wood powder: 20 parts

[0124] DMF: 180 parts;

[0125] Take an appropriate amount of DMF by weight to make the viscosity of the wet foaming material reach a suitable coating viscosity of about 5000 cps.

[0126] The pregelatinized starch and the remaining DMF are mixed to prepare a pregelatinized starch mixture;

[0127] The polyurethane resin mixture and the pregelatinized starch mixture are fully stirred and mixed to obtain a wet foaming material.

[0128] Step 2: Base fabric pretreatment

[0129] The base fabric with a thickness of 0.20 mm was immersed in a DMF aqueous solution with a concentration of 17%, the excess aqueous solution was pressed out with a squeeze roller, and the base fabric was ironed with an ironing wheel, and the humidity was 40%.

[0130] Step 3: Coating and solidification

[0131] The wet foaming material is evenly coated on the pretreated base cloth with a coating gap of 1.00 mm, and then immersed in a coagulation tank with a DMF aqueous solution with a concentration of 20% for coagulation, and the coagulation time is 15 minutes.

[0132] Step 4:

[0133] After complete solidification, it passes through the squeezing roller to squeeze out the excess solidifying liquid, and then passes through the washing tank for washing with 80°C hot water. The first section of the washing tank is for washing with five groups of squeezing rollers, and the second section is for washing with six groups of squeezing rollers. Finally, it is dried, expanded, and shaped to obtain a wet foaming layer.

[0134] Comparative Example 2:

[0135] Step 1: Preparation of wet foaming materials

[0136] Take weight parts:

[0137] 100 parts of polyurethane resin with a solid content of 30% and a modulus of 10 kgf / cm2

[0138] Polyvinyl alcohol: 5 parts

[0139] Wood powder: 20 parts

[0140] DMF: 180 parts;

[0141] Take an appropriate amount of DMF by weight to make the viscosity of the wet foaming material reach a suitable coating viscosity of about 5000 cps.

[0142] The pregelatinized starch and the remaining DMF are mixed to prepare a polyvinyl alcohol mixture;

[0143] The polyurethane resin mixture and the polyvinyl alcohol mixture are fully stirred and mixed to obtain a wet foaming material.

[0144] Step 2: Base fabric pretreatment

[0145] A suede-like base fabric with a thickness of 0.20 mm was immersed in a DMF aqueous solution with a concentration of 17%, and the excess aqueous solution was pressed out with a squeezing roller, and the fabric was ironed with an ironing wheel, and the humidity was 40%.

[0146] Step 3: Coating and solidification

[0147] The wet foaming material is evenly coated on the pretreated base cloth with a coating gap of 1.00 mm, and then immersed in a coagulation tank with a DMF aqueous solution with a concentration of 20% for coagulation, and the coagulation time is 15 minutes.

[0148] Step 4:

[0149] After complete solidification, it passes through the squeezing roller to squeeze out the excess solidifying liquid, and then passes through the washing tank for washing with 80°C hot water. The first section of the washing tank is for washing with five groups of squeezing rollers, and the second section is for washing with six groups of squeezing rollers. Finally, it is dried, expanded, and shaped to obtain a wet foaming layer.

[0150] Comparative Example 3 (the most common clothing leather on the market):

[0151] Step 1: Preparation of wet foaming materials

[0152] Take weight parts:

[0153] 100 parts of polyurethane resin with a solid content of 30% and a modulus of 50 kgf / cm2

[0154] Wood powder: 30 parts

[0155] Light calcium powder: 20 parts

[0156] DMF: 180 parts;

[0157] Take an appropriate amount of DMF by weight to make the viscosity of the wet foaming material reach a suitable coating viscosity of about 5000 cps.

[0158] The wood powder and the remaining DMF are mixed to prepare a pregelatinized starch mixture;

[0159] The polyurethane resin mixture and the wood powder mixture are fully stirred and mixed to obtain a wet foaming material.

[0160] Step 2: Base fabric pretreatment

[0161] A suede-like base fabric with a thickness of 0.20 mm was immersed in a DMF aqueous solution with a concentration of 17%, and the excess aqueous solution was pressed out with a squeezing roller, and the fabric was ironed with an ironing wheel, and the humidity was 40%.

[0162] Step 3: Coating and solidification

[0163] The wet foaming material is evenly coated on the pretreated base cloth with a coating gap of 1.00 mm, and then immersed in a coagulation tank with a DMF aqueous solution with a concentration of 20% for coagulation, and the coagulation time is 15 minutes.

[0164] Step 4:

[0165] After complete solidification, it passes through the squeezing roller to squeeze out the excess solidifying liquid, and then is washed with clean water in a washing tank. The first section of the washing tank is washed with five groups of squeezing rollers, and the second section is washed with six groups of squeezing rollers. Finally, it is dried, expanded, and shaped to obtain a wet foaming layer.

[0166] Ingredients:

[0167]

[0168] The basses obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were faced with the sheepskin obtained in Example 5, as well as the sheepskin for clothing, and then the following tests were carried out.

[0169] test:

[0170] 1. Folding fastness test: QB / T 2714-2018;

[0171] 2. Peel load test: GB / T 2791-1995;

[0172] 3. Jungle test: QB / T 4671-2014; temperature 70°C, relative humidity 95%;

[0173] 4. Softness test: GB / T 39371-2020;

[0174] 5. Indentation test (fold the leather in half and press it with a 50kg iron block with a bottom size of 0.2mX0.2m for 1 hour and then release it. Observe with the naked eye how long it takes for the indentation to disappear);

[0175] 6. Mildew test (place the leather in a mold incubator at a temperature of 28 degrees Celsius and a humidity of 70%, and observe with the naked eye how long it takes to see mold grow).

[0176]

[0177] From the comparison between the embodiments and the comparative examples, it can be found that the folding fastness of embodiments 1 to 4 is obviously better than that of comparative examples 1 to 3, and the peeling load is also better than that of the comparative examples. In the softness test, it can be seen that the softness of comparative examples 1 and 2 is better than that of embodiments 1 and 2 to a certain extent. This is because comparative examples 1 and 2 use pregelatinized starch and polyvinyl alcohol for foaming, and the foaming degree is large, so the bubbles formed are also large, so in terms of softness, they are better than embodiments 1 and 2, but the difference between the two is not large. However, due to the excessively large bubbles, the mechanical properties, such as folding resistance and peeling strength, are poor. Comparative example 3 is prepared with wood powder. Although its foaming is not large compared with pregelatinized starch and polyvinyl alcohol, the wood powder cannot be washed out with water. Therefore, the dried wood powder is harder, and in the process of mechanical testing, it will continuously rub the polyurethane, resulting in the problem of decreased mechanical properties. In the jungle experiment, the embodiments are obviously superior to the comparative examples. The service life of the embodiments is much longer than that of the comparative examples. The service life of the embodiments is more than 12 years, almost exceeding the service life of sheepskin; comparative example 3 is the worst, indicating that the service life of common synthetic clothing leather on the market is less than 2 years. From the indentation test, the indentations of comparative examples 1 to 3 will never disappear. The indentation disappearance time of sheepskin is relatively long, which affects the smoothness and beauty of wearing. The indentation disappearance time of embodiments 1 to 5 is relatively fast, which is conducive to smoothness and beauty of wearing. In the mildew experiment, sheepskin is most likely to breed mold. Comparative examples 1 to 3 are also prone to breed mold. Examples 1 to 4 will not breed mold because the collagen of the dermis and the wood powder of the synthetic leather provide nutrients for the mold.

[0178] On the other hand, Example 3 adds wax and silicone to Example 1, which can effectively improve the softness and surpass the large-cell Comparative Examples 1 and 2 in terms of softness.

[0179] Embodiment 4 adds oil emulsion on the basis of embodiment 1, and the softness can be further improved by adding the oil emulsion.

[0180] The examples 1 and 2 and the comparative examples 1 and 2 were observed by scanning electron microscope. Figure 1 This is the electron microscope image of Example 1, where dense and uniform pores can be seen. Figure 2 The electron microscope image of Example 2 also shows dense and uniform pores, but the pores are slightly larger than those of Example 1. For this reason, the mechanical properties of Example 2 are slightly weaker than those of Example 1. Figure 3 This is the electron microscope image of comparative example 1. It can be seen that the larger bubbles are formed and the bubbles are very uneven. Figure 4 The electron microscope image of comparative example 2 shows relatively large pores, and the formed pores are very uneven, which is the reason why the mechanical properties of comparative examples 1 and 2 are poor.

[0181] The beneficial effects of the present invention are as follows: in the present invention, the foaming material mainly used in the base layer of synthetic leather is mainly a mixture of solvent, polyurethane resin and soluble bio-based powder. The soluble bio-based powder can absorb water and dissolve. During the dissolution process, there will be a long swelling process, and then dissolve again. When swelling, it will expand, thereby forming pores inside the polyurethane resin. When the swelling limit is reached, it will dissolve, thereby dissolving in the solvent, thereby leaving the pores inside the polyurethane. Therefore, when the soluble bio-based powder is used as the foaming material, it will not remain inside the polyurethane.

[0182] Unlike wood powder fillers, which will remain inside the polyurethane after expanding as a foaming agent, and will constantly rub the polyurethane during the continuous bending process, thereby reducing the mechanical properties of the bass. Wood powder is prone to mildew and decay, thereby reducing the weather resistance of the bass.

[0183] In the selection of soluble bio-based powder, the present invention selects modified starch, cyclodextrin, English gum, white dextrin, maltodextrin, and yellow dextrin. The soluble bio-based powder selected by the present invention can be evenly dispersed in the mixture, the wet foaming material is coated on the base cloth and then immersed in the coagulation liquid, the water molecules penetrate into each dextrin powder through DMF, the soluble bio-based powder quickly swells and gelatinizes after encountering water molecules, the soluble bio-based powder and the adjacent parts of the soluble bio-based powder expand and connect with each other during the swelling process, and the swollen soluble bio-based powders are irregularly connected in series with each other; while the soluble bio-based powder expands, the polyurethane resin slowly solidifies when encountering water molecules; after the soluble bio-based powder swells, it continues to dissolve into a dextrin aqueous solution when encountering infiltration water, the soluble bio-based powder aqueous solution and dimethylformamide are cleaned by water in the water washing process, and a foaming layer is obtained by drying, and a special foaming layer with a loofah-like structure is obtained. There is no need to use hot water for washing as in the prior art, or even to add other auxiliary substances for washing.

[0184] Compared with the prior art, the soluble bio-based powder used in the present invention has the ability to dissolve after swelling, and can form relatively uniform and dense bubbles. The synthetic leather produced will not be light, so calcium powder is not needed to increase the weight, but it can have good mechanical properties and weather resistance.

[0185] In the selection of soluble bio-based powders, the preferred performance is to absorb 50% to 200% of its own weight of water to swell, and absorb more than 100% to 400% of its own weight of water to dissolve. The pores formed in this way are relatively dense.

[0186] As a preferred embodiment of the present invention, a proper amount of wax emulsion is added, and the lubrication and astringency of the wax slow down the rebound speed of the foaming layer, making the rebound feel of the resistant leather close to or exceeding that of sheepskin.

[0187] In order to achieve moisture and oiliness, a grease emulsion is added to the wet foaming material. The emulsion plays a role in enhancing the uniform dispersion of powder particles in the wet foaming material, wetting the inner wall of the oil-slip pores to reduce friction, slow down the rebound speed and moisture absorption and weight gain.

[0188] Long-chain amino polyether block silicone oil emulsion is added to the above wet foaming material. Silicone plays a role in uniformly dispersing powder particles in the wet foaming material, reducing the friction between molecules and within the pores, and reducing the softness of the produced foaming layer. In the water washing process, the long-chain amino polyether block silicone oil emulsion is more difficult to be washed out by water than the short-chain amino polyether block silicone oil emulsion, and the softening effect is better.

[0189] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A wet foaming material for resistant skin, characterized in that: include Solvents, polyurethane resins, water-soluble bio-based powders; The water-soluble bio-based powder is composed of one or more of cyclodextrin and yellow dextrin; The water-soluble bio-based powder absorbs 50% to 200% of its own weight of water to swell, and absorbs more than 100% to 400% of its own weight of water to dissolve; The water-soluble bio-based powder is cleaned by water in the water washing process.

2. A wet foaming material for resistant leather according to claim 1, characterized in that: The solvent is dimethylformamide.

3. A wet foaming material for resistant leather according to claim 1, characterized in that: The wet foaming material also includes 1 to 3 parts of wax emulsion.

4. A wet foaming material for resistant leather according to claim 3, characterized in that: The wax emulsion is one or more of paraffin wax emulsion, palm wax emulsion and PE wax emulsion.

5. The wet foaming material for resistant leather according to claim 1, characterized in that: The wet foaming material also includes 4 to 30 parts of organic silicon.

6. A wet foaming material for resistant leather according to claim 5, characterized in that: The organic silicon is long-chain amino polyether block silicone oil or long-chain amino polyether block silicone oil emulsion.

7. The wet foaming material for resistant leather according to claim 1, characterized in that: The mass ratio of the polyurethane resin to the water-soluble bio-based powder is 20-40:30-150.

8. The wet foaming material for resistant leather according to claim 1, characterized in that: It also includes 2 to 15 parts of oil emulsion.

9. The anti-foaming leather prepared by the wet foaming material according to any one of claims 1 to 8, characterized in that: It comprises a textured pavement layer and a wet foaming layer, wherein the wet foaming layer is prepared from the wet foaming material.

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