Soft synthetic leather and method for producing the same

Abstract

The present application relates to a kind of soft synthetic leather, including base cloth layer, wet process base and dry process top layer, the dry process top layer is made of dry process inner layer and dry process outer layer, the dry process inner layer is attached with wet process base, the outer surface of dry process top layer is dry process outer layer, the softness of dry process inner layer is greater than the softness of dry process outer layer, the thickness of dry process inner layer is greater than the thickness of dry process outer layer.The soft synthetic leather is soft, strong, and is cheap and good synthetic leather material, can be applied to clothing leather, bag leather and other decorative material field.

Description

[0001] This application is a divisional application, with its parent application having application number 202210522684.6, an application date of May 13, 2022, and an invention titled "Soft Synthetic Leather and its Preparation Method". Technical Field

[0002] This invention relates to the field of synthetic leather manufacturing technology, to a soft synthetic leather, and to a method for preparing soft synthetic leather. Background Technology

[0003] Due to the limited natural resources and high price of genuine soft leather, it cannot meet the ever-increasing market demand. Synthetic leather, on the other hand, suffers from insufficient softness. To improve the softness of synthetic leather, existing tanneries typically employ a rubbing process, where softeners penetrate the micropores of the leather's base layer to achieve a softening effect. However, because the dry-laid surface layer has a non-porous, dense structure, softeners cannot penetrate it, resulting in a harder feel and a less soft, less pleasant surface texture. The softness of the leather's surface layer is crucial, reflecting the degree of suppleness against the skin; the initial tactile sensation is very important and often determines the leather's quality. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a soft synthetic leather with a delicate feel against the skin.

[0005] The present invention is accomplished by the following technical solution: a soft synthetic leather, comprising a base fabric, a wet-laid base, and a dry-laid surface, wherein the dry-laid surface comprises a dry-laid inner layer and a dry-laid outer layer, the dry-laid inner layer being bonded to the wet-laid base, and the outer surface of the dry-laid surface being the dry-laid outer layer, wherein the softness of the dry-laid inner layer is greater than that of the dry-laid outer layer, and the thickness of the dry-laid inner layer is greater than that of the dry-laid outer layer.

[0006] Furthermore, the thickness of the recessed bottom of the dry outer layer is less than 0.02 mm.

[0007] Furthermore, the dry outer layer is made of a dry outer layer mixture coated on release paper, and the dry inner layer is made of a dry inner layer mixture coated on the dry outer layer.

[0008] Furthermore, the viscosity of the dry outer layer mixture is lower than that of the dry inner layer mixture, and the polyurethane resin content of the dry outer layer mixture is lower than that of the dry inner layer mixture.

[0009] Furthermore, the dry outer layer mixture comprises an outer layer of dry-process polyurethane resin, N,N-dimethylformamide, and colorant, and the dry inner layer mixture comprises an inner layer of dry-process polyurethane resin, N,N-dimethylformamide, and colorant, wherein the modulus of the inner layer of dry-process polyurethane resin is less than 20 kgf / cm³. 2 The modulus of the outer dry-process polyurethane resin is greater than 45 kgf / cm³. 2 .

[0010] Furthermore, the dry outer layer mixture comprises a dry-process silicone polyurethane, N,N-dimethylformamide, and colorant, and the dry inner layer mixture comprises an inner layer dry-process polyurethane resin, N,N-dimethylformamide, and colorant, wherein the modulus of the inner layer dry-process polyurethane resin is less than 20 kgf / cm³. 2 The modulus of the outer dry-process silicone polyurethane layer is greater than 45 kgf / cm³. 2 .

[0011] Furthermore, the dry outer layer mixture comprises a dry-process silicone polyurethane, an outer dry-process polyurethane resin, N,N-dimethylformamide, and colorant; the dry inner layer mixture comprises an inner dry-process polyurethane resin, N,N-dimethylformamide, and colorant; and the modulus of the inner dry-process polyurethane resin is less than 20 kgf / cm³. 2 The modulus of the outer dry-process polyurethane resin is greater than 45 kgf / cm³. 2 The modulus of the outer dry-process silicone polyurethane layer is greater than 45 kgf / cm³. 2 .

[0012] Furthermore, the weight ratio of dry-process silicone polyurethane to outer dry-process polyurethane resin in the dry outer layer mixture is 8:40-150.

[0013] Furthermore, the above-mentioned method for preparing soft synthetic leather includes a base fabric preparation process, a wet-process base fabric preparation process, and a dry-process laminating process, wherein the steps of the dry-process laminating process are as follows:

[0014] (1) Dry mixture preparation, which includes a dry outer layer mixture and a dry inner layer mixture.

[0015] a) The dry outer layer mixture is made by mixing and stirring high-modulus dry polyurethane resin, N,N-dimethylformamide, polyether-modified organosilicon, and color powder evenly, and then degassing.

[0016] b) The dry inner layer mixture is made by mixing and stirring low-modulus dry polyurethane resin, N,N-dimethylformamide, polyether-modified organosilicon, and color powder evenly, and then degassing.

[0017] (2) Dry lamination, including the following steps.

[0018] a) Preparation of release paper coating: The dry outer layer mixture prepared in step 1a is coated on the release paper film with zero gap, and then dried in an oven until semi-dry. The dry inner layer mixture prepared in step 1b is then coated on, and dried in an oven until semi-dry to obtain the release paper coating.

[0019] b) Dry lamination: First, the wet-laid base is pressed onto the release paper coating, then dried in an oven, and cooled by a cooling roller. The release paper and the laminated wet-laid base are then rolled up separately to obtain the finished leather.

[0020] Furthermore, the dry inner layer consists of a dry middle layer and a dry inner layer. The dry inner layer is bonded to the wet base coat. The outer surface of the dry laminate is the dry outer layer. The dry middle layer is located between the dry inner layer and the dry outer layer. Both the dry outer layer and the dry middle layer are colorless and transparent, while the dry inner layer is colored. The dry inner layer and the dry middle layer are more flexible than the dry outer layer. The dry inner layer is thicker than the dry outer layer, and the dry middle layer is thicker than the dry outer layer.

[0021] Furthermore, the above-mentioned method for preparing soft synthetic leather includes a base fabric preparation process, a wet-process base fabric preparation process, and a dry-process laminating process, wherein the steps of the dry-process laminating process are as follows:

[0022] (1) Dry mixture preparation, which includes dry outer layer mixture, dry middle layer mixture and dry inner layer mixture.

[0023] a) The dry outer layer mixture is made by mixing and stirring colorless and transparent high modulus dry polyurethane resin, N,N-dimethylformamide, polyether modified organosilicon, and color powder evenly, and then degassing.

[0024] b) The dry intermediate layer mixture is made by mixing and stirring colorless and transparent low modulus dry polyurethane resin, N,N-dimethylformamide, polyether modified organosilicon, and color powder evenly, and then degassing.

[0025] c) The dry inner layer mixture is made by mixing and stirring colored low-modulus dry polyurethane resin, N,N-dimethylformamide, polyether-modified organosilicon, and color powder evenly, and then degassing.

[0026] (2) Dry lamination, including the following steps.

[0027] a) Preparation of release paper coating: The dry outer layer mixture prepared in step 1a is coated on the release paper film with zero gap, and then dried in an oven until semi-dry. The dry middle layer mixture prepared in step 1b is then coated and dried in an oven until semi-dry. Finally, the dry inner layer mixture prepared in step 1c is coated and dried in an oven until semi-dry to obtain the release paper coating.

[0028] b) Dry lamination: First, the wet-laid base is pressed onto the release paper coating, then dried in an oven, and cooled by a cooling roller. The release paper and the laminated wet-laid base are then rolled up separately to obtain the finished leather.

[0029] Furthermore, the wet-process base includes polyurethane resin, silicone, and filler, with silicone adhering to the micropores of the filler fibers, the micropores and voids inside the polyurethane resin; the weight ratio of polyurethane resin to silicone in the wet-process base is 30:0.5-3.8; the silicone is one or two of amino silicone oil and amino polyether block silicone oil.

[0030] Furthermore, the wet-process base coat is prepared from a wet-process mixture coated on a base fabric. The wet-process mixture comprises a polyurethane resin solvent, a softener, N,N-dimethylformamide, and a filler. The softener includes silicone or a silicone-containing softener. The softener is cationic and has a pH of less than 5. The silicone softener is an amino silicone oil emulsion, an amino polyether block silicone oil emulsion, an amino polyether block silicone oil solvent, or an amino polyether block silicone oil.

[0031] Furthermore, the manufacturing process for the aforementioned soft synthetic leather includes the following steps:

[0032] I. Preparation of mixtures, including the preparation of wet mixtures and dry mixtures.

[0033] 1) Preparation of wet mixture: First, mix and stir the soft silicone emulsion, N,N-dimethylformamide, filler, color paste and other raw materials evenly, then add polyurethane resin solvent and mix and stir evenly, and degas.

[0034] 2) The dry mixture preparation steps are as follows:

[0035] Preparation of the outer layer mixture using a dry process: High-modulus dry polyurethane resin, N,N-dimethylformamide, methyl ethyl ketone, polyether-modified silicone, and colorant are mixed and stirred evenly, and then degassed.

[0036] b. Preparation of dry inner layer mixture: Low modulus dry polyurethane resin, N,N-dimethylformamide, methyl ethyl ketone, polyether modified organosilicon, and color powder are mixed and stirred evenly, and then degassed.

[0037] II. Preparation of wet-process bass:

[0038] 1) Base fabric pretreatment: Immerse the base fabric in an N,N-dimethylformamide aqueous solution with a concentration of 15-25%, press off the excess aqueous solution with a squeeze roller, and iron it flat with an ironing roller at a humidity of 40%.

[0039] 2) Coating and solidification: The wet mixture is evenly coated onto the pretreated base fabric and then immersed in a solidification tank containing a 20% N,N-dimethylformamide aqueous solution for solidification.

[0040] 3) Washing and drying: After complete solidification, the excess solidified liquid is squeezed out by the extrusion rollers, and then washed with clean water in the washing tank. The first section of the washing tank is squeezed by five sets of extrusion rollers, and the second section is squeezed by six sets of extrusion rollers. Finally, the wet-process base is obtained through drying, expansion and shaping.

[0041] III. Dry lamination includes the following steps:

[0042] 1) Preparation of release paper coating: A dry mixture of 2)a is applied to the release paper film with zero gap, and then dried in an oven until semi-dry. Then a dry mixture of 2)b is applied and dried in an oven until semi-dry to obtain the release paper coating.

[0043] 2) Dry lamination: The wet-laid base is directly laminated onto the release paper coating obtained in step 3(1) using pressure, then dried in an oven, cooled by a cooling roller, and the release paper and the laminated wet-laid base are rolled up separately to obtain the finished leather.

[0044] IV. Finished leather surface coating treatment: The front side of the finished leather is coated with a coating agent using three printing plates, and then dried in an oven to obtain the finished leather with the coating effect.

[0045] V. Finished leather texture treatment, including the following steps:

[0046] 1) Add the fabric softener to the rinse tank and mix well;

[0047] 2) Immerse the finished leather in the aqueous solution of the water tank, then dehydrate and roll it dry, and then roll and dry it through the texturer.

[0048] 3) After final inspection, winding, and packaging, a synthetic leather material with a soft feel, a fleshy texture, good strength, and low price will be obtained.

[0049] The beneficial effects achieved by this invention are as follows: 1. In this invention, a multi-coating process is adopted, and a zero-gap coating process is implemented on the release paper film. This achieves the thinnest dry outer layer with a high polyurethane resin modulus, maximizes the thickness ratio of the dry inner layer with a low polyurethane resin modulus to the dry lamination surface, and minimizes the polyurethane resin modulus of the dry inner layer, thus achieving the best soft feel. Currently, to achieve a soft feel with a single dry coating process, the modulus of the dry polyurethane resin can only be reduced. However, dry polyurethane resin with too low a modulus is relatively sticky after drying, which can easily cause leather to stick to other leathers or other items. Therefore, to avoid leather sticking, the soft feel must be sacrificed.

[0050] 2. In this invention, the inner layer of the dry coating uses a dry polyurethane resin with a lower modulus, while the outer layer uses a dry polyurethane resin with a higher modulus. This creates a soft and delicate leather feel, while ensuring that the leather surface is dry and non-sticky, preventing the leather from sticking together. The outermost layer uses a dry polyurethane resin with a higher modulus, which helps the leather surface resist scratches and abrasions. Currently, in dry coating processes, high-modulus dry polyurethane resins cannot be selected to maintain the softness of the leather, resulting in poor scratch and abrasion resistance of the leather surface. To achieve scratch and abrasion resistance, an anti-scratch and abrasion coating needs to be printed, which adds an extra process and increases material costs, drying electricity costs, labor costs, and losses.

[0051] 3. Dry polyurethane resin with lower modulus tends to stick to release paper, making it difficult to peel off and affecting the service life of the release paper. Conversely, dry polyurethane resin with higher modulus is easier to peel off from the release paper, thus improving the service life of the release paper.

[0052] 4. The viscosity of the dry outer layer mixture is relatively low, making it easier to flow on release paper with deeper textures, resulting in clear and precise textures, which is beneficial for the manufacture of deep-textured leather. The polyurethane resin content of the dry outer layer mixture is lower than that of the dry inner layer mixture, so the thickness of the dry outer layer mixture after drying will be thinner, and the feel will be even softer. Detailed Implementation

[0053] To further illustrate the technical means and effects of the present invention in achieving the intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with preferred embodiments, is provided below.

[0054] This invention provides a soft synthetic leather, comprising a base fabric layer, a wet-process base layer, and a dry-process overlay. The dry-process overlay layer consists of a dry-process inner layer and a dry-process outer layer. The inner layer is attached to the base layer, and the outer layer is located away from the base layer. The inner layer is softer than the outer layer, and its thickness is greater than that of the outer layer. The total thickness of the recessed areas of the dry-process overlay on garment leather is generally 0.1-0.15 mm. The thickness of the recessed areas of the dry-process outer layer is less than 0.02 mm, with an optimal thickness of 0.01 mm. The outer layer is made of a dry-process overlay mixture coated on release paper, and the inner layer is made of a dry-process inner layer mixture coated on the outer layer. The release paper is preferably a high-fleece, matte release paper. The inner layer is made of a thick and soft material, while the outer layer is made of a thin and relatively stiff material, thus achieving a soft feel while ensuring the leather does not stick.

[0055] Example 1: The dry-process outer layer mixture in the above-mentioned soft synthetic leather is prepared from an outer layer dry-process polyurethane resin, N,N-dimethylformamide, and colorant. The dry-process inner layer mixture is prepared from an inner layer dry-process polyurethane resin, N,N-dimethylformamide, and colorant. The modulus of the inner layer dry-process polyurethane resin is less than 20 kgf / cm³. 2 The optimal modulus of the inner dry-process polyurethane resin is 10 kgf / cm². 2 The modulus of the outer dry-process polyurethane resin is greater than 45 kgf / cm³. 2 The optimal modulus of the outer dry-process polyurethane resin is 80 kgf / cm². 2 The solid content of both the inner and outer dry-process polyurethane resins is 28-32%, typically 30%.

[0056] The dry outer layer mixture is prepared from the following raw materials in weight percentages:

[0057] Modulus 80 kgf / cm 2 40 parts of dry polyurethane resin,

[0058] 30 parts of N,N-dimethylformamide

[0059] 21.8 parts of methyl ethyl ketone (MEK),

[0060] 0.2 parts leveling agent,

[0061] 8 parts color powder.

[0062] The dry inner layer mixture is prepared from the following raw materials in weight percentages:

[0063] Modulus 10 kgf / cm 2 40 parts of dry polyurethane resin

[0064] 30 parts of N,N-dimethylformamide

[0065] 21.5 parts of methyl ethyl ketone (MEK),

[0066] 0.2 parts leveling agent,

[0067] The amount of emulsifier AEO-3 is 0.3 parts.

[0068] 8 parts color powder.

[0069] Currently, the dry-process polyurethane resin used in garment leather production generally uses 30 kgf / cm³. 2 The modulus is approximately 10 kgf / cm². In this embodiment, the dry inner layer uses a modulus of approximately 10 kgf / cm². 2 The dry-process polyurethane resin has a very soft and delicate feel; the dry-process outer layer uses 80 kgf / cm². 2The modulus of dry polyurethane resin has a very dry feel, good surface scratch and abrasion resistance, good anti-sticking properties, and is easy to demold from release paper, which can prolong the life of release paper.

[0070] In this invention, the dry inner layer that adheres to the base is made of a thick and soft resin to ensure the soft feel of the synthetic leather, while the dry outer layer is made of a thin and non-sticky resin to ensure that the outer surface of the synthetic leather does not stick to other parts. The combination of two dry polyurethane resins with different moduli achieves both a soft feel and high non-stick properties.

[0071] Example 2: The dry outer layer mixture in the above-mentioned soft synthetic leather is prepared from an outer layer dry-process polyurethane resin, N,N-dimethylformamide, and colorant. The viscosity of the dry outer layer mixture is lower than that of the dry inner layer mixture, and the polyurethane resin content of the dry outer layer mixture is lower than that of the dry inner layer mixture. The dry inner layer mixture is prepared from an inner layer dry-process polyurethane resin, N,N-dimethylformamide, and colorant. The modulus of the inner layer dry-process polyurethane resin is less than 20 kgf / cm³. 2 The optimal modulus of the inner dry-process polyurethane resin is 10 kgf / cm². 2 The modulus of the outer dry-process polyurethane resin is greater than 45 kgf / cm³. 2 The optimal modulus of the outer dry-process polyurethane resin is 80 kgf / cm². 2 The solid content of both the inner and outer dry-process polyurethane resins is 28-32%, typically 30%.

[0072] The dry outer layer mixture is prepared from the following raw materials in weight percentages:

[0073] Modulus 80 kgf / cm 2 30 parts of dry polyurethane resin,

[0074] 35 parts of N,N-dimethylformamide

[0075] 25.8 parts of methyl ethyl ketone (MEK),

[0076] 0.2 parts leveling agent,

[0077] 8 parts color powder.

[0078] The dry inner layer mixture is prepared from the following raw materials in weight percentages:

[0079] Modulus 10 kgf / cm 2 40 parts of dry polyurethane resin

[0080] 30 parts of N,N-dimethylformamide

[0081] 21.5 parts of methyl ethyl ketone (MEK),

[0082] 0.2 parts leveling agent,

[0083] The amount of emulsifier AEO-3 is 0.3 parts.

[0084] 8 parts color powder.

[0085] Currently, the viscosity of dry-process mixing solutions used in garment leather production is generally around 3000. In this embodiment, the viscosity of the dry-process outer layer mixing solution is approximately 2000, and the viscosity of the dry-process inner layer mixing solution is approximately 3000. The polyurethane resin content of the dry-process outer layer mixing solution is 9%, and the polyurethane resin content of the dry-process inner layer mixing solution is 12%. In this embodiment, the relatively lower viscosity of the dry-process outer layer mixing solution is beneficial for the manufacture of deep-grained leather; the lower polyurethane resin content of the dry-process outer layer mixing solution allows for a thinner dry-process outer layer.

[0086] Example 3: The dry-process outer layer mixture in the above-mentioned soft synthetic leather is prepared from dry-process silicone polyurethane, N,N-dimethylformamide, and colorant. The dry-process inner layer mixture is prepared from inner-layer dry-process polyurethane resin, N,N-dimethylformamide, and colorant. The modulus of the inner-layer dry-process polyurethane resin is less than 20 kgf / cm³. 2 The optimal modulus of the inner dry-process polyurethane resin is 10 kgf / cm². 2 The modulus of the outer dry-process silicone polyurethane layer is greater than 45 kgf / cm³. 2 The optimal modulus of the outer dry-process silicone polyurethane layer is 70 kgf / cm³. 2 The inner layer of dry-process polyurethane resin has a solid content of 28-32%, typically 30%. The outer layer of dry-process silicone polyurethane has a solid content of 28-32%, typically 30%.

[0087] The dry outer layer mixture is prepared from the following raw materials in weight percentages:

[0088] Modulus 70 kgf / cm 2 40 parts of dry-processed organosilicon polyurethane

[0089] 30 parts of N,N-dimethylformamide

[0090] 21.8 parts of methyl ethyl ketone (MEK),

[0091] 0.2 parts leveling agent,

[0092] 8 parts color powder.

[0093] The dry-process inner layer mixture is prepared from the following raw materials in weight percentages:

[0094] Modulus 10 kgf / cm 2 40 parts of dry-process polyurethane resin

[0095] 30 parts of N,N-dimethylformamide

[0096] 21.5 parts of methyl ethyl ketone (MEK),

[0097] 0.2 parts leveling agent,

[0098] The amount of emulsifier AEO-3 is 0.3 parts.

[0099] 8 parts color powder.

[0100] The beneficial effects of this embodiment:

[0101] 1. During the synthesis of polyurethane resin, organosilicon is attached, which makes dry-process organosilicon polyurethane not only soft and smooth to the touch, with a strong skin feel, deep and bright colors, and high non-stick properties, but also more than three times the cost of polyurethane resin. Therefore, the inner layer of dry-process polyurethane resin is made of soft and thick dry-process polyurethane resin, while the outer layer is made of dry-process organosilicon polyurethane. This reduces costs while ensuring the softness and high non-stick properties of the outer layer of synthetic leather.

[0102] 2. In the dry lamination process, when the release paper for the high-slip, matte finish is made of polyurethane resin, an organosilicon leveling agent is added to facilitate demolding and increase the number of uses. However, the amount of organosilicon leveling agent added should not exceed 0.3% of the total weight. If excessive amounts are added, the produced leather will develop spots on the surface after a period of time due to the release agent precipitating out, increasing the loss rate. Therefore, it is necessary to limit the amount of leveling agent while ensuring leather quality. The number of uses for the release paper is generally around 10. If the release paper for the high-slip, matte finish is made of silicone polyurethane, the smooth and insulating properties of silicone polyurethane far outweigh those of the organosilicon leveling agent, and the number of uses for the release paper is generally over 50. High-slip, matte finish release paper is expensive; this invention can significantly reduce costs.

[0103] 3. The velvet surface has a particularly prominent haze and vibrancy, which enhances the visual appeal and improves the tactile feel of the velvet, giving it a slightly smooth and soft, skin-like texture.

[0104] Example 4: The dry-process outer layer mixture in the above-mentioned soft synthetic leather is prepared from dry-process silicone polyurethane, outer layer dry-process polyurethane resin, N,N-dimethylformamide, and colorant. The dry-process inner layer mixture is prepared from inner layer dry-process polyurethane resin, N,N-dimethylformamide, and colorant. The modulus of the inner layer dry-process polyurethane resin is less than 20 kgf / cm³. 2 The preferred modulus of the inner dry-process polyurethane resin is 10 kgf / cm². 2 The modulus of the outer dry-process polyurethane resin is greater than 45 kgf / cm³. 2 The optimal modulus of the outer dry-process polyurethane resin is 80 kgf / cm². 2The modulus of the outer dry-process silicone polyurethane layer is greater than 45 kgf / cm³. 2 The optimal modulus of dry-process silicone polyurethane is 70 kgf / cm². 2 .

[0105] The weight ratio of the dry-process outer layer mixture to the outer layer dry-process polyurethane resin is 8:40-150, with the most preferred ratio being 8:100. The solid content of both the inner and outer layer dry-process polyurethane resins is 28-32%, typically 30%. The solid content of the outer layer dry-process silicone polyurethane is also 28-32%, typically 30%.

[0106] The dry outer layer mixture is prepared from the following raw materials in weight percentages:

[0107] Modulus 70 kgf / cm 2 5 parts of dry-processed silicone polyurethane

[0108] Modulus 80 kgf / cm 2 50 parts of dry polyurethane resin,

[0109] 42 parts of N,N-dimethylformamide

[0110] 15 parts of butyl acetate

[0111] 8 parts color powder.

[0112] The dry inner layer mixture is prepared from the following raw materials in weight percentages:

[0113] Modulus 10 kgf / cm 2 30 parts of dry polyurethane resin,

[0114] Modulus 15 kgf / cm 2 10 parts of dry polyurethane resin,

[0115] 30 parts of N,N-dimethylformamide

[0116] 21.5 parts of methyl ethyl ketone (MEK),

[0117] 0.2 parts leveling agent,

[0118] The amount of emulsifier AEO-3 is 0.3 parts.

[0119] 8 parts color powder.

[0120] When the release paper for the high-fleece texture is made of a combination of silicone polyurethane and polyurethane resin, the release paper can be used nearly 50 times, further reducing costs. Compared with the leather suede surface made of polyurethane resin, the haze, vibrancy, smoothness, and skin feel are all significantly improved.

[0121] In this invention, the method for preparing the above-mentioned soft synthetic leather includes a base fabric preparation process, a wet-process base fabric preparation process, and a dry-process laminating process, wherein the dry-process laminating preparation steps are as follows:

[0122] (1) Preparation of dry mixture, which includes dry outer layer mixture and dry inner layer mixture, is prepared as follows:

[0123] a) The dry outer layer mixture is made by mixing and stirring high-modulus dry polyurethane resin, N,N-dimethylformamide, polyether-modified organosilicon, and color powder evenly, and then degassing.

[0124] b) The dry inner layer mixture is made by mixing and stirring low-modulus dry polyurethane resin, N,N-dimethylformamide, polyether-modified organosilicon, and color powder until uniform and degassed.

[0125] (2) Dry lamination includes the following steps:

[0126] a) Preparation of release paper coating: The dry outer layer mixture prepared in step 1 is coated on the release paper film with zero gap, and then dried in an oven until semi-dry. The dry inner layer mixture prepared in step 1 is then coated on, and dried in an oven until semi-dry to obtain the release paper coating.

[0127] b) Dry lamination: First, the wet-laid base is pressed onto the release paper coating, then dried in an oven, and cooled by a cooling roller. The release paper and the laminated wet-laid base are then rolled up separately to obtain the finished leather.

[0128] In this embodiment of the dry lamination preparation process, the dry outer layer mixture is coated on the release paper film with zero gaps. This can achieve a thickness of less than 0.02mm at the bottom of the textured outer layer, maximizing the thickness of the soft inner layer and achieving maximum softness while ensuring non-stick properties.

[0129] Example 5: The aforementioned soft synthetic leather includes a base fabric layer, a wet-laid base layer, and a dry-laid surface layer. The dry-laid surface layer consists of a dry-laid inner layer and a dry-laid outer layer. The dry-laid inner layer consists of a dry-laid middle layer and a dry-laid inner layer. The dry-laid inner layer is bonded to the wet-laid base layer. The outer surface of the dry-laid surface layer is the dry-laid outer layer. The dry-laid middle layer is located between the dry-laid inner layer and the dry-laid outer layer. Both the dry-laid outer layer and the dry-laid middle layer are colorless and transparent, while the dry-laid inner layer is colored. The softness of the dry-laid inner layer and the dry-laid middle layer is greater than that of the dry-laid outer layer. The thickness of the dry-laid inner layer is greater than that of the dry-laid outer layer, and the thickness of the dry-laid middle layer is greater than that of the dry-laid outer layer. The thickness of the dry-laid outer layer is 0.015 mm, the thickness of the dry-laid middle layer is 0.08 mm, and the thickness of the dry-laid outer layer is 0.04 mm.

[0130] The outer dry-process mixture is prepared from a colorless and transparent outer dry-process polyurethane resin and N,N-dimethylformamide. The middle dry-process mixture is prepared from a colorless and transparent middle dry-process polyurethane resin and N,N-dimethylformamide. The inner dry-process mixture is prepared from an inner dry-process polyurethane resin, N,N-dimethylformamide, and colorant. The modulus of the middle and inner dry-process polyurethane resins is less than 20 kgf / cm³. 2 The optimal modulus of the dry-process polyurethane resin in the middle and inner layers is 10 kgf / cm². 2 The modulus of the outer dry-process polyurethane resin is greater than 45 kgf / cm³. 2 The optimal modulus of the outer dry-process polyurethane resin is 80 kgf / cm². 2 The dry-process polyurethane resin in the inner, middle, and outer layers all has a solid content of 28-32%, typically 30%.

[0131] The dry outer layer mixture is prepared from the following raw materials in weight percentages:

[0132] Modulus 80 kgf / cm 2 40 parts of colorless and transparent dry-process polyurethane resin,

[0133] 38 parts of N,N-dimethylformamide

[0134] 21.8 parts of methyl ethyl ketone (MEK),

[0135] 0.2 parts leveling agent.

[0136] The dry intermediate layer mixture is prepared from the following raw materials in weight percentages:

[0137] Modulus 10 kgf / cm 2 40 parts of colorless and transparent dry-process polyurethane resin.

[0138] 38 parts of N,N-dimethylformamide

[0139] 21.5 parts of methyl ethyl ketone (MEK),

[0140] 0.2 parts leveling agent,

[0141] The amount of emulsifier AEO-3 is 0.3 parts.

[0142] The dry-process inner layer mixture is prepared from the following raw materials in weight percentages:

[0143] Modulus 10 kgf / cm 2 40 parts of dry polyurethane resin,

[0144] 30 parts of N,N-dimethylformamide

[0145] 21.5 parts of methyl ethyl ketone (MEK),

[0146] 0.2 parts leveling agent,

[0147] The amount of emulsifier AEO-3 is 0.3 parts.

[0148] 8 parts color powder.

[0149] The steps of the dry lamination process are as follows:

[0150] (1) Dry mixture preparation, which includes dry outer layer mixture, dry middle layer mixture and dry inner layer mixture.

[0151] a) The dry outer layer mixture is made by mixing and stirring colorless and transparent high modulus dry polyurethane resin, N,N-dimethylformamide, polyether modified organosilicon, and color powder evenly, and then degassing.

[0152] b) The dry intermediate layer mixture is made by mixing and stirring colorless and transparent low modulus dry polyurethane resin, N,N-dimethylformamide, polyether modified organosilicon, and color powder evenly, and then degassing.

[0153] c) The dry inner layer mixture is made by mixing and stirring colored low-modulus dry polyurethane resin, N,N-dimethylformamide, polyether-modified organosilicon, and color powder evenly, and then degassing.

[0154] (2) Dry lamination, including the following steps.

[0155] a) Preparation of release paper coating: The dry outer layer mixture prepared in step 1a is coated on the release paper film with zero gap, and then dried in an oven until semi-dry. The dry middle layer mixture prepared in step 1b is then coated and dried in an oven until semi-dry. Finally, the dry inner layer mixture prepared in step 1c is coated and dried in an oven until semi-dry to obtain the release paper coating.

[0156] b) Dry lamination: First, the wet-laid base is pressed onto the release paper coating, then dried in an oven, and cooled by a cooling roller. The release paper and the laminated wet-laid base are then rolled up separately to obtain the finished leather.

[0157] The beneficial effects of this embodiment are as follows: because the outer and middle layers are colorless and transparent, while the inner layer is colored, the resulting leather texture has a crystal-clear visual effect, as well as a soft feel, anti-sticking, anti-scratch, and anti-wear properties. It is suitable for producing leathers with special visual effects such as pearl patterns, coarse textures, and full textures, providing new leather products and achieving high added value.

[0158] Example 6: In the aforementioned soft synthetic leather, the dry-laid surface comprises a dry inner layer and a dry outer layer. The dry inner layer is bonded to the wet-laid base coat. The outer surface of the dry-laid surface is the dry outer layer. The softness of the dry inner layer is greater than that of the dry outer layer, and the thickness of the dry inner layer is greater than that of the dry outer layer. The thickness of the textured bottom of the dry outer layer is less than 0.02 mm, with an optimal thickness of 0.015 mm. The wet-laid base coat comprises polyurethane resin, silicone, and filler. Silicone is attached to the micropores of the filler fibers, the micropores and voids inside the polyurethane resin, and the inner walls of the foam cells formed when the filler fibers shrink. The weight ratio of polyurethane resin to silicone in the wet-laid base coat is 30:0.5-3.8, with an optimal ratio of 30:1.5. The silicone is one or two of amino silicone oil and amino polyether block silicone oil.

[0159] The preparation of soft synthetic leather includes the preparation of wet-process base and the preparation of dry-process lamination.

[0160] The dry outer layer mixture is prepared from an outer layer of dry-process polyurethane resin, N,N-dimethylformamide, and colorant. The dry inner layer mixture is prepared from an inner layer of dry-process polyurethane resin, N,N-dimethylformamide, and colorant. The modulus of the inner layer of dry-process polyurethane resin is less than 20 kgf / cm³. 2 The optimal modulus of the inner dry-process polyurethane resin is 10 kgf / cm². 2 The modulus of the outer dry-process polyurethane resin is greater than 45 kgf / cm³. 2 The optimal modulus of the outer dry-process polyurethane resin is 80 kgf / cm². 2 The solid content of both the inner and outer dry-process polyurethane resins is 28-32%, typically 30%.

[0161] The wet-process base coat is prepared by a wet-process mixture coated on a base fabric. The wet-process mixture comprises a polyurethane resin solvent, an amino polyether block silicone oil emulsion, N,N-dimethylformamide, and fillers. The amino polyether block silicone oil emulsion is cationic with a pH less than 5, and an optimal pH of 2.2. The polyurethane resin solvent has a solid content of 28-32%, typically 30%.

[0162] The dry outer layer mixture is prepared from the following raw materials in weight percentages:

[0163] Modulus 80 kgf / cm 2 40 parts of dry polyurethane resin,

[0164] 30 parts of N,N-dimethylformamide

[0165] 21.8 parts of methyl ethyl ketone (MEK),

[0166] 0.2 parts leveling agent,

[0167] 8 parts color powder.

[0168] The dry inner layer mixture is prepared from the following raw materials in weight percentages:

[0169] Modulus 10 kgf / cm 2 40 parts of dry polyurethane resin

[0170] 30 parts of N,N-dimethylformamide

[0171] 21.5 parts of methyl ethyl ketone (MEK),

[0172] 0.2 parts leveling agent,

[0173] The amount of emulsifier AEO-3 is 0.3 parts.

[0174] 8 parts color powder.

[0175] The wet-process mixture is prepared from the following raw materials in weight percentages:

[0176] Modulus 5 kgf / cm 2 27 parts of wet-process polyurethane resin solvent solution,

[0177] Modulus 10 kgf / cm 2 12 parts of wet-process polyurethane resin solvent solution,

[0178] 3 parts cationic silicone emulsion

[0179] 46 parts of N,N-dimethylformamide

[0180] 12 parts of wood fiber powder.

[0181] Furthermore, the manufacturing process for the aforementioned soft synthetic leather includes the following steps:

[0182] I. Preparation of mixtures, including the preparation of wet mixtures and dry mixtures.

[0183] 1) Preparation of wet mixture: First, mix and stir the soft silicone emulsion, N,N-dimethylformamide, filler, color paste and other raw materials evenly, then add polyurethane resin solvent and mix and stir evenly, and degas.

[0184] 2) The dry mixture preparation steps are as follows:

[0185] Preparation of the outer layer mixture using a dry process: High-modulus dry polyurethane resin, N,N-dimethylformamide, methyl ethyl ketone, polyether-modified silicone, and colorant are mixed and stirred evenly, and then degassed.

[0186] b. Preparation of dry inner layer mixture: Low modulus dry polyurethane resin, N,N-dimethylformamide, methyl ethyl ketone, polyether modified organosilicon, and color powder are mixed and stirred evenly, and then degassed.

[0187] II. Preparation of wet-process bass:

[0188] 1) Base fabric pretreatment: Immerse the base fabric in an N,N-dimethylformamide aqueous solution with a concentration of 15-25%, press off the excess aqueous solution with a squeeze roller, and iron it flat with an ironing roller at a humidity of 40%.

[0189] 2) Coating and solidification: The wet mixture is evenly coated onto the pretreated base fabric and then immersed in a solidification tank containing a 20% N,N-dimethylformamide aqueous solution for solidification.

[0190] 3) Washing and drying: After complete solidification, the excess solidified liquid is squeezed out by the extrusion rollers, and then washed with clean water in the washing tank. The first section of the washing tank is squeezed by five sets of extrusion rollers, and the second section is squeezed by six sets of extrusion rollers. Finally, the wet-process base is obtained through drying, expansion and shaping.

[0191] III. Dry lamination includes the following steps:

[0192] 1) Preparation of release paper coating: A dry mixture of 2)a is applied to the release paper film with zero gap, and then dried in an oven until semi-dry. Then a dry mixture of 2)b is applied and dried in an oven until semi-dry to obtain the release paper coating.

[0193] 2) Dry lamination: The wet-laid base is directly laminated onto the release paper coating obtained in step 3(1) using pressure, then dried in an oven, cooled by a cooling roller, and the release paper and the laminated wet-laid base are rolled up separately to obtain the finished leather.

[0194] IV. Finished leather texture treatment, including the following steps:

[0195] 1) Add the fabric softener to the rinse tank and mix well;

[0196] 2) Immerse the finished leather in the aqueous solution of the water tank, then dehydrate and roll it dry, and then roll and dry it through the texturer.

[0197] 3) Final inspection, winding, and packaging will yield synthetic leather material that is soft to the touch, has a fleshy texture, good strength, and is inexpensive.

[0198] The soft silicone adsorbs into the pores and voids of the bass filler, acting as a lubricant to reduce the coefficient of friction and resulting in a soft and comfortable feel. The soft silicone emulsion acts as a uniform disperser in the wet mixture, ensuring even dispersion of the wood fiber filler. After coating the wet mixture, it undergoes washing and drying in a coagulation tank. The shrinkage of the wood fiber filler forms a uniformly distributed pore structure, resulting in a strong, foamy feel. Simultaneously, the soft silicone emulsion is encapsulated by the polyurethane resin solvent. After coating the wet mixture and washing and drying in a coagulation tank, very dense micropores containing soft silicone are formed within the resin, making the bass filler exceptionally soft. The soft silicone is adsorbed into the pores and between the fibers of the wood fiber filler, contributing to the filler's softness. The soft silicone is primarily adsorbed within the pores and voids of the bass filler; very little soft silicone is carried away by water during the coagulation tank washing process. Because the soft silicone is liquid, the solvent recovery system is less prone to clogging. Because wet-process base relies on the softening effect of soft silicone, there is no need for excessively dense pores, resulting in good strength, peel strength, and tear strength.

[0199] In addition, by using a multi-coating process and a zero-gap coating process on the release paper film, the outer dry layer with a high polyurethane resin modulus is made the thinnest, the thickness ratio of the inner dry layer with a low polyurethane resin modulus is maximized, and the polyurethane resin modulus of the inner dry layer is minimized, resulting in the best soft feel.

[0200] This embodiment achieves the ultimate softness for both the bass and the overlay, while the leather surface is also non-sticky, scratch-resistant, and wear-resistant, making the quality of synthetic leather surpass that of genuine leather, realizing the high-end development of synthetic leather, and greatly increasing the added value of the product.

[0201] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing soft synthetic leather, characterized in that: The process includes the preparation of the base fabric, the preparation of the wet-process base layer, and the preparation of the dry-process facing. The dry-process facing consists of a dry-process inner layer and a dry-process outer layer. The dry-process inner layer is bonded to the wet-process base layer, and the outer surface of the dry-process facing is the dry-process outer layer. The softness of the dry-process inner layer is greater than that of the dry-process outer layer, and the thickness of the dry-process inner layer is greater than that of the dry-process outer layer. The thickness of the textured concave bottom of the dry-process outer layer is less than 0.02 mm. The raw material for the dry outer layer includes dry-process silicone polyurethane. The preparation steps for the dry-process laminate are as follows: (1) Dry mixture preparation, which includes a dry outer layer mixture and a dry inner layer mixture. a) The dry outer layer mixture comprises high-modulus dry-process polyurethane resin, N,N-dimethylformamide, polyether-modified silicone, dry-process silicone polyurethane, and colorant, which are mixed and stirred evenly and then degassed; the modulus of the high-modulus dry-process polyurethane resin is greater than 45 kgf / cm³. 2 ; b) The dry inner layer mixture comprises low-modulus dry-process polyurethane resin, N,N-dimethylformamide, polyether-modified silicone, and colorant, which are mixed and stirred evenly and then degassed; the modulus of the low-modulus dry-process polyurethane resin is less than 20 kgf / cm³. 2 ; (2) Dry lamination, including the following steps. a) Preparation of release paper coating: The dry outer layer mixture prepared in step 1a is coated with a special fog high-velvet release paper film with zero gap, and then dried in an oven until semi-dry. The dry inner layer mixture prepared in step 1b is then coated and dried in an oven until semi-dry to obtain the release paper coating. b) Dry lamination: First, the wet-laid base is pressed onto the release paper coating, then dried in an oven and cooled by a cooling roller. The special matte high-suede release paper and the laminated wet-laid base are rolled up separately to obtain the finished leather.

2. The method for preparing soft synthetic leather according to claim 1, characterized in that: The weight ratio of dry-process silicone polyurethane to outer dry-process polyurethane resin in the dry outer layer mixture is 8:40-150.

3. The method for preparing soft synthetic leather according to claim 1 or 2, characterized in that: The wet-process base includes polyurethane resin, silicone, and filler. The weight ratio of polyurethane resin to silicone in the wet-process base is 30:0.5-3.

8. The silicone is one or two of amino silicone oil and amino polyether block silicone oil.

4. The method for preparing soft synthetic leather according to claim 1, characterized in that: The dry outer layer is made of a dry outer layer mixture coated on release paper, and the dry inner layer is made of a dry inner layer mixture coated on the dry outer layer.

5. The method for preparing soft synthetic leather according to claim 4, characterized in that: The viscosity of the dry outer layer mixture is lower than that of the dry inner layer mixture, and the polyurethane resin content of the dry outer layer mixture is lower than that of the dry inner layer mixture.

6. The method for preparing soft synthetic leather according to claim 1, characterized in that: The modulus of the outer dry-process silicone polyurethane layer is greater than 45 kgf / cm³. 2 .

7. The method for preparing soft synthetic leather according to claim 1, 2, 4, 5, or 6, characterized in that: The dry inner layer consists of a dry middle layer and a dry inner layer. The dry inner layer is bonded to the wet base layer. The outer surface of the dry laminate is the dry outer layer. The dry middle layer is located between the dry inner layer and the dry outer layer. Both the dry outer layer and the dry middle layer are colorless and transparent, while the dry inner layer is colored. The softness of the dry inner layer and the dry middle layer is greater than that of the dry outer layer. The thickness of the dry inner layer is greater than that of the dry outer layer, and the thickness of the dry middle layer is greater than that of the dry outer layer.

8. The method for preparing soft synthetic leather as described in claim 3, characterized in that: Organosilicon is attached to the micropores of the filler fibers and the micropores and voids inside the polyurethane resin; the wet-process base is prepared by a wet-process mixture coated on the base fabric, the wet-process mixture comprising a polyurethane resin solvent, a softener, N,N-dimethylformamide and a filler, the softener comprising organosilicon or an organosilicon softener containing organosilicon, the ionic type of the softener being cationic, the pH of the organosilicon softener being less than 5, and the organosilicon softener being an amino silicone oil emulsion or an amino polyether block silicone oil emulsion or an amino polyether block silicone oil solvent or an amino polyether block silicone oil.