Surface-treatment-free PVC artificial leather and manufacturing method thereof

Abstract

The embodiment of the invention provides surface-treatment-free PVC artificial leather. The surface-treatment-free PVC artificial leather comprises a functional PVC surface layer, a PVC foaming layer, a glue layer and a base cloth layer, wherein the functional PVC surface layer at least contains PVC resin, a plasticizer, linear polydimethylsiloxane, talcum powder, hollow glass beads and a thermal reversible cross-linking agent, and does not contain a polyurethane surface treatment layer. According to the surface-treatment-free PVC artificial leather, the failure risk of a polyurethane surface treating agent layer is eradicated, a series of interface reliability problems of interlayer adhesion reduction, surface layer swelling, softening, pulverization and the like caused by plasticizer migration are fundamentally eliminated by canceling the polyurethane surface treating agent layer, the long-term durability of the product is qualitatively improved, and the service life of the product is prolonged. The performance of the material is derived from the material body, and even if the surface is worn due to long-term use, the newly exposed material still has the same chemical components and functions, so that the stable performance of the product is realized.

Description

Technical Field

[0001] This invention relates to the field of artificial leather, specifically to a surface-treatment-free PVC artificial leather and its manufacturing method. Background Technology

[0002] In the automotive interior manufacturing industry, polyvinyl chloride (PVC) artificial leather has long been widely used for covering components such as seats, door panels, dashboards, and armrests due to its excellent durability, ease of processing, and cost-effectiveness. To meet the automotive industry's high standards for aesthetics, comfort, and durability, mainstream automotive interior PVC artificial leather typically employs a multi-layered composite structure. This structure consists of five layers of materials with different functions, which together determine the overall performance of the final product. The first layer is a polyurethane surface treatment layer, which is crucial for giving the artificial leather its excellent surface properties. It directly determines the product's feel, visual gloss, scratch resistance, and abrasion resistance. A high-quality polyurethane surface layer can effectively simulate the delicate feel of natural leather. The first layer provides lasting protection. The second layer is the PVC outer layer, which constitutes the main color and texture of the artificial leather. Through embossing, various imitation leather or other natural textures can be formed on this layer. The third layer is the PVC foam layer, which is made by adding foaming agents to the PVC formula. Its main function is to provide a soft padding feel and enhance riding comfort. The fourth layer is the PVC adhesive layer, whose core function is to act as a strong adhesive to firmly bond the upper PVC plastic layer with the bottom base fabric layer. The fifth base fabric layer is usually made of knitted or woven fabric made of fibers such as polyester or nylon. As the skeleton of the entire material, it provides the artificial leather with the necessary mechanical strength, dimensional stability and tear resistance, ensuring that it does not deform under long-term use and stress. In terms of production technology, the industry generally adopts a step-by-step processing method. The first step is the manufacture of the PVC preform (i.e., the four layers remaining after removing the polyurethane surface treatment layer, including the PVC skin layer, PVC foam layer, PVC adhesive layer, and base fabric layer). There are two main production line technologies: one is the coating production line, which mixes PVC paste resin, plasticizer, stabilizer, and other formulation materials, and then evenly coats them onto the base fabric using a scraper or roller. Subsequently, it undergoes gelation, foaming, and plasticizing oven drying to form the PVC preform. The other is the calendering production line, which calenders the mixed PVC dry blend through a high-temperature process. The calender rolls the film into a film of a specified thickness, and then laminates it with the base fabric under pressure to form a dense PVC preform. Regardless of the production method, the PVC preform must proceed to the next critical process: surface treatment. This process must be completed on a separate printing production line. Using gravure printing technology, the prepared polyurethane surface treatment agent is evenly applied to the surface of the PVC preform, and then it is cross-linked and cured in a high-temperature drying tunnel to finally form a high-performance polyurethane surface treatment agent layer. This two-step production mode is currently the mature and mainstream preparation solution in the field of PVC artificial leather for automotive interiors. The disadvantages of conventional technology: The polyurethane surface treatment layer and the underlying PVC layer (including the skin layer and foam layer) are two different polymer materials with different chemical properties. This difference may not be apparent initially, but throughout the product's life cycle, especially under long-term environmental stresses such as heat, oxygen, and ultraviolet radiation, it can lead to potential interfacial stability problems. The core mechanism is that in order to obtain the necessary flexibility, PVC materials require the addition of a large amount of small-molecule plasticizers, such as phthalates, in the formulation. These plasticizers are mainly bonded to the PVC molecular chains through physical interactions rather than strong chemical bonds. Over time and under the influence of the usage environment, such as the high and low temperature cycles experienced by automotive interiors over many years, the plasticizers will inevitably and persistently leach from the PVC body. As plasticizers continue to migrate to the surface, they can have two negative effects on the polyurethane material when they reach and penetrate the polyurethane surface treatment agent layer. As a small molecule solvent, plasticizers can penetrate into the network structure of polyurethane macromolecules, causing them to swell. This leads to softening of the coating material and a decrease in strength. The direct consequence is a significant deterioration in the coating's abrasion resistance, scratch resistance, and hydrolysis resistance, making the surface more susceptible to scratches and wear. Furthermore, the migration of plasticizers can form a weak boundary layer at the PU / PVC interface, which may dissolve the adhesive substances at the interface or change the stress state of the interface, resulting in a decrease in interlayer adhesion. This not only accelerates the failure of surface functions but may even, in extreme cases, cause localized peeling between the PU layer and the PVC underlayer, resulting in irreversible cosmetic damage. The current two-step production method, while technologically mature, is essentially a measure taken to compensate for the insufficient surface properties of the PVC substrate. This method and the resulting coating structure pose a hidden danger to the long-term durability of artificial leather. The thickness of the polyurethane surface treatment layer applied by printing / coating is usually strictly controlled between a few micrometers and tens of micrometers. Its excellent touch, gloss, and wear resistance depend entirely on the integrity of this outer layer. In the daily use of automotive interiors, parts such as seats and door panels will continuously endure mechanical actions such as friction and pressure. Once this extremely thin polyurethane coating is locally worn through, the underlying PVC material will be directly exposed. PVC material is far inferior to polyurethane in terms of touch, gloss, and wear resistance, resulting in a precipitous drop in the overall performance of the product. This means that the effective service life of the product is largely limited by this extremely thin surface treatment layer, and the potential of the entire thick PVC substrate and base fabric is not fully realized, leaving room for improvement. Summary of the Invention

[0003] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a surface-treatment-free PVC artificial leather and its manufacturing method to solve the aforementioned problems.

[0004] (II) Technical Solution To achieve the above objectives, at least one embodiment of this disclosure provides a surface-treatment-free PVC artificial leather, comprising a functional PVC outer skin layer, a PVC foam layer, an adhesive layer, and a base fabric layer; The functional PVC skin layer contains at least PVC resin, plasticizer, linear polydimethylsiloxane, talc, hollow glass microspheres and thermally reversible crosslinking agent, but does not contain a polyurethane surface treatment layer.

[0005] For example, in at least one embodiment of the PVC artificial leather provided in this disclosure, the functional PVC outer layer is formed from a raw material comprising the following parts by weight: 100 parts of PVC resin Phthalate plasticizer 70-100 parts, 5-15 parts of linear polydimethylsiloxane 5-15 parts talcum powder 0.5-5 parts of hollow glass microspheres 0.5-2 parts of thermally reversible crosslinking agent.

[0006] For example, in the surface-treatment-free PVC artificial leather provided in at least one embodiment of this disclosure, the viscosity of the linear polydimethylsiloxane is selected from one or more of 350 mm² / s, 500 mm² / s, and 1000 mm² / s.

[0007] For example, in the surface-treatment-free PVC artificial leather provided in at least one embodiment of this disclosure, the talc powder has a mesh size selected from one or more of 500 mesh, 1000 mesh, 1500 mesh and 2000 mesh.

[0008] For example, in the surface-treatment-free PVC artificial leather provided in at least one embodiment of this disclosure, the hollow glass microspheres have a density of 0.125-0.46 g / cm³ and a particle size selected from one or more of 20 micrometers, 35 micrometers, and 65 micrometers.

[0009] For example, in the surface-treatment-free PVC artificial leather provided in at least one embodiment of this disclosure, the thermally reversible crosslinking agent is one or both of zinc dicyclopentadienedicarboxylate or sodium dicyclopentadienedicarboxylate.

[0010] For example, in at least one embodiment of the present disclosure, the surface texture of the functional PVC skin layer is formed by replicating the surface pattern of the release paper.

[0011] For example, in at least one embodiment of the PVC artificial leather provided in this disclosure, the 60-degree gloss of the functional PVC surface layer is less than 2.0.

[0012] According to another aspect of the present invention, a functional epidermal layer composition for PVC artificial leather is also provided, comprising, by weight, the following components: 100 parts of PVC resin; Phthalate plasticizers, 70-100 parts; 5-15 parts of linear polydimethylsiloxane; 5-15 parts talcum powder; 0.5-5 parts of hollow glass microspheres; 0.5-2 parts of thermally reversible crosslinking agent.

[0013] (III) Beneficial Effects Compared with the prior art, the present invention provides a surface-treatment-free PVC artificial leather and its manufacturing method, which has the following beneficial effects: This invention eliminates the failure risk of the polyurethane surface treatment agent layer. By eliminating the polyurethane surface treatment agent layer, it fundamentally eliminates a series of interface reliability problems caused by plasticizer migration, such as decreased interlayer adhesion, surface swelling, softening, and powdering, thereby significantly improving the long-term durability of the product. The performance of this invention originates from the material itself. Even if the surface wears down due to long-term use, the newly exposed material still has the same chemical composition and function, thus avoiding the precipitous drop in performance of traditional products and achieving stable performance throughout the product's entire life cycle. Furthermore, the introduction of cross-linking technology gives the PVC skin layer higher thermal stability, reducing the risk of material softening, sticking, or even decomposition in high-temperature environments, and improving the safety and reliability of the product in extreme environments. Moreover, traditional solvent-based polyurethane surface treatment agents are the main source of VOCs in the production process. This invention eliminates this process, thereby eliminating the emission of such VOCs at the source, greatly improving the working environment, and reducing air pollution. By using recognized safe substances such as linear polydimethylsiloxane, talc, and hollow glass microspheres to construct surface functions, the polyurethane system, which may contain residual isocyanate monomers, is replaced, making the final product more suitable for scenarios such as automotive interiors and furniture that come into close contact with the human body. By combining the traditional two-step process into continuous production, the intermediate steps of material winding, storage, transportation, and re-preparation are eliminated. Furthermore, integrated production allows for a high concentration of quality control points. Through precise control of key process parameters on a single production line, the uniformity and stability of the final product performance can be guaranteed, greatly reducing the complexity and uncertainty of quality management and effectively improving the product yield. Detailed Implementation

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] It should be understood that in the various embodiments of the present invention, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0016] It should be understood that in this invention, "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0017] The inventors discovered through research that the polyurethane surface treatment layer and the underlying PVC layer (including the skin layer and the foaming layer) are two polymer materials with different chemical properties. This difference may not be apparent initially, but throughout the product's lifecycle, especially under long-term environmental stresses such as heat, oxygen, and ultraviolet radiation, it can lead to potential interfacial stability issues. The core mechanism lies in the fact that to achieve the necessary flexibility, PVC requires the addition of a large amount of small-molecule plasticizers, such as phthalates, to the formulation. These plasticizers are primarily bonded to the PVC molecular chains through physical interactions, rather than strong chemical bonds. Over time and with changes in the usage environment, such as the constant high and low temperature cycles experienced by automotive interiors, plasticizers inevitably and continuously migrate from the interior of the PVC matrix to the surface. When the migrating plasticizers reach and penetrate the polyurethane surface treatment layer, they have two negative impacts on the polyurethane material: Firstly, as a small-molecule solvent, the plasticizer can penetrate into the network structure of the polyurethane macromolecules, causing swelling, which in turn softens the coating material and reduces its strength. The direct consequence is a significant deterioration in the coating's abrasion resistance, scratch resistance, and hydrolysis resistance, making the surface more susceptible to scratches and wear. Furthermore, the migration of plasticizers can cause damage at the PU / PVC interface. A weak boundary layer can dissolve adhesive substances at the interface or alter the stress state, leading to decreased interlayer adhesion. This not only accelerates the failure of surface functions but, in extreme cases, can even cause localized peeling between the PU layer and the PVC substrate, resulting in irreversible cosmetic damage. The currently used two-step production method, while technologically mature, is essentially a measure to compensate for the insufficient surface properties of the PVC substrate. This method and the resulting coating structure pose a hidden risk to the long-term durability of artificial leather. The thickness of the polyurethane surface treatment agent layer applied through printing / coating is typically strictly controlled to a few micrometers to tens of micrometers. Between the micrometers, its excellent touch, gloss, and abrasion resistance depend entirely on the integrity of this outer layer. In the daily use of automotive interiors, parts such as seats and door panels are constantly subjected to mechanical actions such as friction and pressure. Once this extremely thin polyurethane coating is partially worn through, the underlying PVC material will be directly exposed. PVC is far inferior to polyurethane in terms of touch, gloss, and abrasion resistance, resulting in a precipitous drop in the overall performance of the product. This means that the effective lifespan of the product is largely limited by this extremely thin surface treatment agent, and the potential of the entire thick PVC substrate and base fabric is not fully realized, leaving room for improvement.

[0018] Based on the above ideas, at least one embodiment of this disclosure provides a surface-treatment-free PVC artificial leather, characterized in that it comprises a functional PVC outer skin layer, a PVC foam layer, an adhesive layer, and a base fabric layer; wherein the functional PVC outer skin layer contains at least PVC resin, plasticizer, linear polydimethylsiloxane, talc, hollow glass microspheres, and a thermally reversible crosslinking agent, and does not contain a polyurethane surface treatment layer; the functional PVC outer skin layer is formed from raw materials comprising the following weight parts: 100 parts of PVC resin Phthalate plasticizer 70-100 parts, 5-15 parts of linear polydimethylsiloxane 5-15 parts talcum powder 0.5-5 parts of hollow glass microspheres 0.5-2 parts of thermally reversible crosslinking agent; The viscosity of the linear polydimethylsiloxane is selected from one or more of 350 mm² / s, 500 mm² / s, and 1000 mm² / s; the mesh size of the talc is selected from one or more of 500 mesh, 1000 mesh, 1500 mesh, and 2000 mesh; the density of the hollow glass microspheres is 0.125-0.46 g / cm³, and the particle size is selected from one or more of 20 micrometers, 35 micrometers, and 65 micrometers; the thermally reversible crosslinking agent is one or both of zinc dicyclopentadienedicarboxylate and sodium dicyclopentadienedicarboxylate; the surface texture of the functional PVC skin layer is formed by replicating the surface pattern of the release paper; the 60-degree gloss of the functional PVC skin layer is less than 2.0.

[0019] According to another aspect of the present invention, a method for preparing surface-treated PVC artificial leather is also provided, comprising the following steps: A functional PVC skin layer slurry is prepared, comprising the following components by weight: 100 parts PVC resin, 70-100 parts phthalate plasticizer, 5-15 parts linear polydimethylsiloxane, 5-15 parts talc, 0.5-5 parts hollow glass microspheres, and 0.5-2 parts thermally reversible crosslinking agent. A functional PVC surface layer slurry is coated onto patterned release paper, dried in an oven, followed by a PVC foaming layer slurry, dried in an oven, and then an adhesive layer slurry. The base fabric and adhesive layer slurry are then wet-bonded, dried in an oven, cooled, and peeled off from the patterned release paper to obtain artificial leather.

[0020] According to another aspect of the present invention, a functional epidermal layer composition for PVC artificial leather is also provided, comprising, by weight, the following components: 100 parts of PVC resin; Phthalate plasticizers, 70-100 parts; 5-15 parts of linear polydimethylsiloxane; 5-15 parts talcum powder; 0.5-5 parts of hollow glass microspheres; 0.5-2 parts of thermally reversible crosslinking agent.

[0021] The following describes a surface-treatment-free PVC artificial leather and its manufacturing method provided by the present disclosure through several specific embodiments.

[0022] Example 1 Surface-treatment-free PVC artificial leather was prepared according to the functional PVC outer layer formulation in Table 1. The PVC foam layer, adhesive layer, and base fabric layer are commercially available materials, and conventional materials well-known to those skilled in the art can be selected as needed. The detailed preparation method is as follows: Step 1: Mix and stir the components of the functional PVC outer layer according to the specified ratio until homogeneous; Step 2: Vacuum degas the well-stirred slurry under a certain rotation speed; Step 3: Filter the degassed slurry through a sieve to obtain the functional PVC skin layer slurry; Step 4: Using the release paper coating method, the coating gap is controlled, and the functional PVC skin layer slurry is coated on low-gloss, high-temperature resistant patterned release paper, which is then baked and cured in a high-temperature oven. Step 5: Using the release paper coating method, control the coating gap, apply PVC foaming layer slurry to the functional PVC skin layer that has been cured in step 4, and bake it in a high-temperature oven to foam and cure it. Step Six: Using the release paper coating method, control the coating gap, apply the adhesive layer slurry to the foaming layer in Step Five, then wet-attach the base fabric to the surface of the adhesive layer, bake and cure in a high-temperature oven, and peel off to obtain the surface treatment agent-free PVC artificial leather.

[0023] Table 1. Functional PVC Surface Layer Formulation of Example 1 Example 2 The difference between this embodiment and Embodiment 1 lies in the formulation of the functional PVC outer layer, as shown in Table 2. The preparation process is exactly the same as that of Embodiment 1.

[0024] Table 2 Functional PVC Skin Layer Formulation of Example 2 Comparative Example 1 This comparative example simulates ordinary PVC artificial leather without surface treatment. Its PVC surface layer formula contains only 100 parts of PVC resin, 80 parts of diisononyl phthalate, and 10 parts of other functional additives. No linear polydimethylsiloxane, talc, hollow glass microspheres, or thermally reversible crosslinking agent are added. The specific details are shown in Table 3. The preparation process is the same as in Example 1.

[0025] Table 3 shows the functional PVC outer layer formulation of Comparative Example 1. Comparative Example 2 In this comparative example of functional PVC skin layer formulation, no linear polydimethylsiloxane was added. The remaining components and amounts were the same as in Example 2, as shown in Table 4. The preparation process was the same as in Example 1.

[0026] Table 4. Functional PVC Surface Formulation for Comparative Example 2 Comparative Example 3 In this comparative example of functional PVC skin layer formulation, talc and hollow glass microspheres are not added. The remaining components and their amounts are the same as in Example 2, as shown in Table 5. The preparation process is the same as in Example 1.

[0027] Table 5 shows the functional PVC outer layer formulation of Comparative Example 3. Comparative Example 4 In this comparative example of functional PVC skin layer formulation, no thermally reversible crosslinking agent is added. The remaining components and dosages are the same as in Example 2, as shown in Table 6. The preparation process is the same as in Example 1.

[0028] Table 6 shows the functional PVC outer skin formulation for Comparative Example 4. Key performance tests were conducted on the artificial leather samples obtained in Examples 1 and 2 and Comparative Examples 1-4, and the results are shown in Table 7.

[0029] Table 7 Performance Test Data It should be noted that the PVC foam layer, adhesive layer, and base fabric layer are commercially available materials, and conventional materials familiar to those skilled in the art can be selected as needed.

[0030] It should be noted that the weight percentages of other adjuvants in each example remain consistent at 10 parts.

[0031] The results show that the artificial leather prepared in Examples 1 and 2 both exhibit excellent comprehensive performance, with a smooth and dry feel, a gloss level as low as 1.0 at 60 degrees, and a wear resistance that meets the 4-level qualification standard. This confirms that the present invention, through a specific formula and one-step process, can produce artificial leather that meets the high-end requirements of automotive interiors without the need for an additional polyurethane surface treatment layer. Compared with Comparative Example 1, which is a plain PVC skin layer without any functional additives, its performance is completely degraded, proving that the formula of the present invention is the fundamental reason for the performance improvement. Compared with Comparative Example 2, Comparative Example 2 lacked linear polydimethylsiloxane, resulting in a rougher feel, significantly reduced abrasion resistance, and disappearance of the pattern. This proves that polydimethylsiloxane is crucial for providing a smooth feel and basic abrasion resistance. Compared with Comparative Example 3, Comparative Example 3 lacked talc powder and hollow glass microspheres, resulting in increased gloss, a wet and sticky feel, and decreased wear resistance. This proves that the combination of talc powder and hollow glass microspheres not only synergistically achieved deep matting but also improved the dry touch of the surface and enhanced wear resistance through microscopic support. Compared with Comparative Example 4, Comparative Example 4 lacked thermally reversible crosslinking agent. Although the feel and gloss were acceptable, the wear resistance was still unqualified. This proves that thermally reversible crosslinking agent significantly improves the heat resistance and mechanical strength of the skin layer by constructing a crosslinking network, so that it can still maintain the surface integrity under frictional heat generation conditions, which is the key to achieving high standard wear resistance. The above results fully demonstrate that the present invention eliminates the risk of PU / PVC interface failure; performance originates from the substrate, with no precipitous drop after wear; and the process is simplified, environmentally friendly, and highly efficient.

[0032] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A surface-treatment-free PVC artificial leather, characterized in that, It includes a functional PVC outer skin layer, a PVC foam layer, an adhesive layer, and a base fabric layer; The functional PVC skin layer contains at least PVC resin, plasticizer, linear polydimethylsiloxane, talc, hollow glass microspheres and thermally reversible crosslinking agent, but does not contain a polyurethane surface treatment layer.

2. The surface-treatment-free PVC artificial leather according to claim 1, characterized in that, The functional PVC outer layer is formed from raw materials comprising the following parts by weight: 100 parts of PVC resin Phthalate plasticizer 70-100 parts, 5-15 parts of linear polydimethylsiloxane 5-15 parts talcum powder 0.5-5 parts of hollow glass microspheres 0.5-2 parts of thermally reversible crosslinking agent.

3. The surface-treatment-free PVC artificial leather according to claim 2, characterized in that, The viscosity of the linear polydimethylsiloxane is selected from one or more of 350 mm² / s, 500 mm² / s, and 1000 mm² / s.

4. The surface-treatment-free PVC artificial leather according to claim 2, characterized in that, The talc powder has a mesh size selected from one or more of 500 mesh, 1000 mesh, 1500 mesh and 2000 mesh.

5. The surface-treatment-free PVC artificial leather according to claim 2, characterized in that, The hollow glass microspheres have a density of 0.125-0.46 g / cm³ and a particle size selected from one or more of 20 micrometers, 35 micrometers, and 65 micrometers.

6. The surface-treatment-free PVC artificial leather according to claim 2, characterized in that, The thermally reversible crosslinking agent is one or both of zinc dicyclopentadienedicarboxylate or sodium dicyclopentadienedicarboxylate.

7. The surface-treatment-free PVC artificial leather according to any one of claims 1-6, characterized in that, The surface texture of the functional PVC skin layer is formed by replicating the surface pattern of the release paper.

8. The surface-treatment-free PVC artificial leather according to any one of claims 1-7, characterized in that, The functional PVC skin layer has a 60-degree gloss level of less than 2.

0.

9. A functional epidermal layer composition for PVC artificial leather, characterized in that, It contains the following components in parts by weight: 100 parts of PVC resin; Phthalate plasticizers, 70-100 parts; 5-15 parts of linear polydimethylsiloxane; 5-15 parts talcum powder; 0.5-5 parts of hollow glass microspheres; 0.5-2 parts of thermally reversible crosslinking agent.

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