A new type of high-breathability microporous PU leather and a preparation process thereof

Abstract

The application discloses a novel high-breathability microporous PU leather and a preparation process thereof, and belongs to the technical field of leather.The novel high-breathability microporous PU leather comprises a base cloth layer, a PU breathability bonding layer and a dry-process breathability PU grain layer in sequence; the base cloth layer is a pure polyester warp-knitted fabric, has double-side fluff and forms a breathability micropore in the interior; the PU breathability bonding layer comprises polyurethane, breathability auxiliary agent particles and a crosslinking agent; the dry-process breathability PU grain layer comprises polyurethane resin, breathability fine powder particles, breathability auxiliary agent particles and pigments, and is provided with a natural grain imitation surface; and the preparation process comprises layer-by-layer coating, drying, lamination and peeling off release paper.The novel high-breathability microporous PU leather has a breathability of 3.5 mg / (cm2*h) or more, a tensile strength of 15 MPa or more and an elongation at break of 300% or more, and can be widely applied to the fields of clothes, shoes, bags, furniture, automobile interiors and the like.

Description

Technical Field

[0001] This invention belongs to the field of leather technology, specifically relating to a novel high-breathability microporous PU leather and its preparation process. Background Technology

[0002] PU synthetic leather, also known as polyurethane synthetic leather, is composed of a base fabric and a polyurethane coating layer. Because its appearance, texture, and mechanical properties are close to those of natural leather, and it has advantages such as low cost, short production cycle, and better environmental performance than natural leather (reducing the environmental burden caused by animal farming and slaughter), it has been widely used in the fields of bags, clothing, footwear, vehicles, and furniture, becoming an important alternative material to natural leather.

[0003] However, the polyurethane polymer resin in traditional PU leather crystallizes to form excellent film-forming properties and a dense molecular structure, inherently creating a sealed, waterproof, and non-breathable surface layer. This inherent defect results in its breathability being far inferior to that of natural leather. Especially when used in clothing, footwear, and other intimate apparel, it cannot effectively expel heat and sweat from the skin, leading to stuffiness, discomfort, and unpleasant odors over time. This severely impacts the user experience and limits the expansion of PU leather into high-end product markets.

[0004] Currently, while there are some attempts at breathable PU leather in existing technologies, most achieve breathability by simply creating micropores or adding breathable additives. However, these methods suffer from problems such as unstable breathability, easy clogging of micropores, decreased mechanical properties, complex production processes, and high costs, making it difficult to balance breathability, mechanical properties, and production feasibility. Furthermore, some breathable PU leathers rely on petrochemical raw materials, resulting in high chemical consumption during production, which does not meet the requirements of sustainable development.

[0005] Furthermore, with consumers' increasing demands for product comfort and environmental friendliness, and the stringent requirements of high-end manufacturing for material performance, developing a new type of breathable PU leather with excellent breathability, stable mechanical properties, environmentally friendly production, and controllable costs has become a pressing technical problem for the leather industry. Based on this, this invention proposes a novel breathable PU leather to overcome the shortcomings of existing technologies. Summary of the Invention

[0006] (1) Technical solution This invention provides a novel high-breathability microporous PU leather, which comprises, from bottom to top: a base fabric layer, a PU breathable bonding layer, and a dry-process breathable PU textured layer; The base fabric layer is a pure polyester warp-knitted fabric with a thickness of 1.2-1.4mm, a specification of 75D 72F 32 needles, double-sided napped, and breathable micropores formed inside the base fabric; The PU breathable bonding layer has a thickness of 0.05-0.15mm and includes polyurethane, breathable additive particles, and crosslinking agent; The dry-process breathable PU textured layer has a thickness of 0.05-0.1mm and includes dry-process polyurethane resin, breathable fine powder particles, breathable additive particles, and pigments, with a textured surface that resembles natural leather.

[0007] Preferably, the breathable micropores inside the base fabric have a pore size of 100nm-50μm and a micropore density of 500-1200 pores / cm².

[0008] Preferably, the coating material of the PU breathable bonding layer includes, by weight, 80-120 parts of polyurethane resin, 30-70 parts of DMF, 3-12 parts of breathable additive particles, and 1.5-6 parts of crosslinking agent.

[0009] Preferably, the coating raw materials of the dry-process breathable PU textured layer include, by weight, 80-120 parts of polyurethane resin, 50-110 parts of DMF, 10-35 parts of methyl ester, 4-14 parts of breathable fine powder particles, 3-12 parts of breathable additive particles, and 8-25 parts of pigment.

[0010] Preferably, the breathable additive particles are polyacrylic acid resin particles with a particle size of 50nm-20μm, and the amount added is 5-10% of the weight of polyurethane.

[0011] Preferably, the breathable fine powder particles are ultrafine wood fiber particles and ultrafine calcium carbonate powder particles, and the mass ratio of the ultrafine wood fiber particles to the ultrafine calcium carbonate powder particles is 1:1.

[0012] Preferably, the crosslinking agent in the PU breathable bonding layer is an isocyanate crosslinking agent, and the amount added is 2-4% of the weight of the polyurethane.

[0013] As a further preferred embodiment, the coating material of the PU breathable bonding layer includes, by weight, 100 parts of polyurethane resin, 50 parts of DMF, 6 parts of breathable additive particles, and 4 parts of crosslinking agent.

[0014] As a further preferred embodiment, the coating raw materials of the dry-process breathable PU textured layer include, by weight, 100 parts of polyurethane resin, 80 parts of DMF, 20 parts of methyl methacrylate, 8 parts of breathable fine powder particles, 6 parts of breathable additive particles, and 15 parts of pigment.

[0015] This invention also provides a novel process for preparing highly breathable microporous PU leather, comprising the following steps: (1) Mix all the raw materials of the dry breathable PU textured layer evenly, coat it on the dry release paper to form a textured surface layer, and then dry it at 100-120℃; (2) Mix the raw materials of the PU breathable bonding layer evenly, coat them on the textured layer after drying in step (1) to form a bonding layer, and then dry at 100-120℃; (3) The base fabric layer is attached to the bonding layer obtained in step (2) and dried at 120-150℃ to make the base fabric, PU breathable bonding layer and dry breathable PU textured layer tightly bonded together. (4) Cool and peel off the release paper to obtain the novel high-permeability microporous PU leather.

[0016] (2) Beneficial effects Compared with the prior art, the present invention has the following outstanding advantages: 1. Excellent breathability: This invention utilizes a multi-layered structural design. The base fabric layer is directly connected to the leather surface through a special bonding layer, creating interconnected breathable micropores and channels. Breathable PU bonding layer and dry-process breathable PU textured layer are embedded with breathable particles, forming a three-dimensional interpenetrating porous network structure. This significantly improves the breathability and moisture-wicking capacity of PU leather, achieving a breathability rate of over 3.5 mg / (cm²·h) and a water absorption rate of over 65%. It can quickly expel heat and sweat emitted by the human body, avoiding stuffiness and odor, improving wearing and usage comfort, and solving the core defect of poor breathability in traditional PU leather.

[0017] 2. Stable mechanical properties: By optimizing the proportion of each layer and the preparation process, this invention improves breathability while ensuring the tensile strength, elongation at break, and abrasion resistance of PU leather. The tensile strength is ≥15MPa and the elongation at break is ≥300%, meeting the usage requirements of different scenarios such as clothing, footwear, and automotive interiors, and avoiding the problem of declining mechanical properties of existing breathable PU leather.

[0018] 3. Multifunctional: The functional treatment layer gives PU leather waterproof, antibacterial and soft properties at the same time. The waterproof agent can effectively block water penetration, the antibacterial agent can inhibit the growth of bacteria and further reduce odor, and the softener enhances the feel and texture, making it close to natural leather, which can meet the quality requirements of high-end products.

[0019] 4. Environmentally friendly and scalable production: This invention uses polyurethane as the main raw material, and the preparation process is simple. It can be mass-produced using conventional coating, drying, and embossing equipment, resulting in high production efficiency and controllable costs. Compared with existing breathable PU leather production processes, it is more in line with the needs of sustainable development.

[0020] 5. Wide range of applications: The novel breathable PU leather prepared by this invention combines breathability, comfort, mechanical properties and environmental friendliness. It can be widely used in clothing, footwear, bags, furniture, automotive interiors and other fields. It has broad market application prospects, can replace some natural leather, reduce the use of animal leather and achieve a win-win situation of environmental protection and practicality. Attached Figure Description

[0021] Figure 1This is a photograph of the novel highly breathable microporous PU leather of this invention. Detailed Implementation Example 1

[0022] This embodiment provides a novel highly breathable microporous PU leather and its preparation process.

[0023] Base fabric layer: pure polyester warp-knitted fabric, 1.3mm thick, 75D 72F 32 gauge, double-sided napped, the breathable micropores inside the base fabric have a pore size of 100nm-50μm and a micropore density of 800 pores / cm².

[0024] Dry-process breathable PU textured layer raw material ratio (parts by weight): 100 parts polyurethane resin, 80 parts DMF, 20 parts methyl ester, 8 parts breathable fine powder particles (ultra-fine wood fiber particles and ultra-fine calcium carbonate powder particles, mass ratio 1:1), 6 parts breathable additive particles (polyacrylic resin particles, particle size 50nm-20μm), and 15 parts pigment.

[0025] PU breathable bonding layer raw material ratio (parts by weight): 100 parts polyurethane resin, 50 parts DMF, 6 parts breathable additive particles (polyacrylic resin particles, particle size 50nm-20μm), and 4 parts isocyanate crosslinking agent.

[0026] Preparation process: (1) Mix the dry breathable PU textured layer raw materials evenly, coat them on the dry release paper, the coating thickness is 0.08mm, and dry at 110℃; (2) Mix the PU breathable bonding layer material evenly and coat it onto the textured layer of step (1). The coating thickness is 0.10 mm and it is dried at 110°C. (3) Lay the base fabric layer onto the bonding layer and dry it at 135°C to ensure that the layers are tightly bonded; (4) After cooling, peel off the release paper to obtain the finished product.

[0027] Tests showed that the PU leather obtained in this embodiment has an air permeability of 3.8 mg / (cm²•h), a water absorption rate of 68%, a tensile strength of 16.2 MPa, an elongation at break of 320%, a clear surface texture, a soft feel, and no stuffiness. Example 2

[0028] The difference between this embodiment and Embodiment 1 lies in the different raw material ratios, as detailed below: Dry-process breathable PU textured layer raw material ratio (parts by weight): 90 parts polyurethane resin, 65 parts DMF, 18 parts methyl ester, 7 parts breathable fine powder particles (ultra-fine wood fiber particles and ultra-fine calcium carbonate powder particles, mass ratio 1:1), 5 parts breathable additive particles (polyacrylic acid resin particles, particle size 50nm-20μm), and 13 parts pigment.

[0029] PU breathable bonding layer raw material ratio (parts by weight): 90 parts polyurethane resin, 42 parts DMF, 5 parts breathable additive particles (polyacrylic resin particles, particle size 50nm-20μm), and 3.5 parts crosslinking agent.

[0030] The base fabric layer and preparation process are the same as in Example 1.

[0031] The obtained PU leather was tested and found to have an air permeability of 3.6 mg / (cm²•h), a water absorption rate of 66%, a tensile strength of 15.8 MPa, and an elongation at break of 315%, demonstrating excellent performance. Example 3

[0032] The difference between this embodiment and Embodiment 1 lies in the different raw material ratios, as detailed below: Dry-process breathable PU textured layer raw material ratio (parts by weight): 110 parts polyurethane resin, 95 parts DMF, 28 parts methyl ester, 11 parts breathable fine powder particles (ultra-fine wood fiber particles and ultra-fine calcium carbonate powder particles, mass ratio 1:1), 9 parts breathable additive particles (polyacrylic resin particles, particle size 50nm-20μm), and 20 parts pigment.

[0033] PU breathable bonding layer raw material ratio (parts by weight): 110 parts polyurethane resin, 58 parts DMF, 9 parts breathable additive particles (polyacrylic resin particles, particle size 50nm-20μm), and 5.5 parts crosslinking agent.

[0034] The base fabric layer and preparation process are the same as in Example 1.

[0035] Tests showed that the obtained PU leather had an air permeability of 4.1 mg / (cm²•h), a water absorption rate of 71%, a tensile strength of 16.7 MPa, and an elongation at break of 328%, demonstrating excellent performance. Example 4

[0036] The difference between this embodiment and Embodiment 1 lies in the different parameters of the base fabric layer, as detailed below: Base fabric: pure polyester warp-knitted fabric, 1.2mm thick, 75D 72F 32 gauge, double-sided napped, breathable micropores with a pore size of 100nm-50μm and a micropore density of 500 pores / cm².

[0037] The raw material ratio and preparation process are the same as in Example 1.

[0038] Tests showed that the obtained PU leather had an air permeability of 3.5 mg / (cm²•h), a water absorption rate of 65%, a tensile strength of 16.0 MPa, and an elongation at break of 318%, demonstrating excellent performance. Example 5

[0039] The difference between this embodiment and Embodiment 1 lies in the different parameters of the base fabric layer, as detailed below: Base fabric: pure polyester warp-knitted fabric, 1.4mm thick, 75D 72F 32 gauge, double-sided napped, breathable micropores with a pore size of 100nm-50μm and a micropore density of 1200 pores / cm².

[0040] The raw material ratio and preparation process are the same as in Example 1.

[0041] Tests showed that the obtained PU leather had an air permeability of 4.0 mg / (cm²•h), a water absorption rate of 69%, a tensile strength of 16.3 MPa, and an elongation at break of 322%, demonstrating excellent performance.

[0042] Comparative Example 1 The difference from Example 1 is that no breathable additive particles or breathable fine powder particles are added to either the dry-process breathable PU textured layer or the PU breathable bonding layer; otherwise, they are the same. The resulting PU leather has a breathability of only 0.5 mg / (cm²•h), resulting in a noticeable stuffy feeling.

[0043] Comparative Example 2 The difference from Example 1 is that the base fabric layer uses ordinary polyester plain weave fabric, without napping treatment, and does not have a breathable microporous structure. Everything else is the same. The resulting PU leather has an air permeability of 0.8 mg / (cm²•h), which is significantly lower than that of Example 1.

[0044] The novel high-breathability microporous PU leather and its preparation process provided by this invention can be mass-produced continuously using conventional coating, drying, and laminating equipment, resulting in high production efficiency and controllable costs. The obtained PU leather has excellent breathability and stable mechanical properties, and can be widely used in clothing, footwear, bags, furniture, automotive interiors, and other fields, possessing good industrial practical value and market prospects.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A novel highly breathable microporous PU leather, characterized in that, From bottom to top, it includes: base fabric layer, breathable PU bonding layer, and dry breathable PU textured layer; The base fabric layer is a pure polyester warp-knitted fabric with a thickness of 1.2-1.4mm, a specification of 75D 72F 32 needles, double-sided napped, and breathable micropores formed inside the base fabric; The PU breathable bonding layer has a thickness of 0.05-0.15mm and includes polyurethane, breathable additive particles, and crosslinking agent; The dry-process breathable PU textured layer has a thickness of 0.05-0.1mm and includes dry-process polyurethane resin, breathable fine powder particles, breathable additive particles, and pigments, with a textured surface that resembles natural leather.

2. The novel high-breathability microporous PU leather according to claim 1, characterized in that, The breathable micropores inside the base fabric have a pore size of 100nm-50μm and a micropore density of 500-1200 pores / cm².

3. The novel high-breathability microporous PU leather according to claim 1, characterized in that, The coating materials of the PU breathable bonding layer include, by weight, 80-120 parts of polyurethane resin, 30-70 parts of DMF, 3-12 parts of breathable additive particles, and 1.5-6 parts of crosslinking agent.

4. The novel high-breathability microporous PU leather according to claim 1, characterized in that, The coating materials of the dry-process breathable PU textured layer include, by weight, 80-120 parts of polyurethane resin, 50-110 parts of DMF, 10-35 parts of methyl methacrylate, 4-14 parts of breathable fine powder particles, 3-12 parts of breathable additive particles, and 8-25 parts of pigment.

5. The novel high-breathability microporous PU leather according to claim 1, characterized in that, The breathable additive particles are polyacrylic acid resin particles with a particle size of 50nm-20μm, and the amount added is 5-10% of the weight of polyurethane.

6. The novel high-breathability microporous PU leather according to claim 1, characterized in that, The breathable fine powder particles are ultrafine wood fiber particles and ultrafine calcium carbonate powder particles, and the mass ratio of the ultrafine wood fiber particles to the ultrafine calcium carbonate powder particles is 1:

1.

7. The novel high-breathability microporous PU leather according to claim 1, characterized in that, The crosslinking agent in the PU breathable bonding layer is an isocyanate crosslinking agent, and the amount added is 2-4% of the weight of the polyurethane.

8. The novel high-breathability microporous PU leather according to claim 3, characterized in that, The coating materials of the PU breathable bonding layer include, by weight, 100 parts of polyurethane resin, 50 parts of DMF, 6 parts of breathable additive particles, and 4 parts of crosslinking agent.

9. The novel high-breathability microporous PU leather according to claim 4, characterized in that, The coating materials of the dry-process breathable PU textured layer include, by weight, 100 parts of polyurethane resin, 80 parts of DMF, 20 parts of methyl methacrylate, 8 parts of breathable fine powder particles, 6 parts of breathable additives, and 15 parts of pigment.

10. A preparation process for a novel high-breathability microporous PU leather according to any one of claims 1-9, characterized in that, Includes the following steps: (1) Mix all the raw materials of the dry breathable PU textured layer evenly, coat it on the dry release paper to form a textured surface layer, and then dry it at 100-120℃; (2) Mix the raw materials of the PU breathable bonding layer evenly, coat them on the textured layer after drying in step (1) to form a bonding layer, and then dry at 100-120℃; (3) The base fabric layer is attached to the bonding layer obtained in step (2) and dried at 120-150℃ to make the base fabric, PU breathable bonding layer and dry breathable PU textured layer tightly bonded together. (4) Cool and peel off the release paper to obtain the novel high-permeability microporous PU leather.

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