How to Make PVC Synthetic Leather

Introduction

PVC synthetic leather, also known as PVC artificial leather, is a popular alternative to natural leather due to its affordability, durability, and versatility. It is widely used in various industries, including automotive, furniture, fashion, and footwear. In this article, we will explore the process of making PVC synthetic leather, from the selection of raw materials to the final production steps.

Raw Materials Selection

The first step in making PVC synthetic leather is to select the appropriate raw materials. The main components of PVC synthetic leather include PVC resin, plasticizers, stabilizers, additives, and a base material.

• PVC Resin: PVC resin is the primary ingredient in PVC synthetic leather. It provides the basic structure and properties of the leather. There are different types of PVC resins available, such as suspension PVC resin and emulsion PVC resin, each with its own characteristics and applications. For example, suspension PVC resin is commonly used for the production of PVC synthetic leather due to its good processability and mechanical properties.
• Plasticizers: Plasticizers are added to PVC resin to increase its flexibility, softness, and workability. There are two main types of plasticizers: high - molecular polyester plasticizers and organic bio - based plasticizers. High - molecular polyester plasticizers can improve the heat resistance and durability of the leather, while organic bio - based plasticizers are more environmentally friendly. The amount of plasticizers used usually ranges from 20 - 140 parts by weight, depending on the desired properties of the final product.
• Stabilizers: Stabilizers are used to prevent the degradation of PVC resin during processing and use. They can improve the heat stability, light stability, and weather resistance of the leather. Common stabilizers include calcium - zinc composite metal soap stabilizers and solid composite calcium - zinc soap stabilizers. The amount of stabilizers added is typically 2 - 6 parts by weight.
• Additives: Additives are used to enhance specific properties of the PVC synthetic leather, such as anti - oxidation, anti - ultraviolet, and anti - static properties. For example, antioxidants can prevent the leather from oxidizing and aging, while anti - ultraviolet agents can protect the leather from the damage of ultraviolet rays. The amount of additives is usually 5 - 6 parts by weight.
• Base Material: The base material provides support and strength to the PVC synthetic leather. Common base materials include cloth and paper. The choice of base material depends on the intended application of the leather. For example, in automotive interiors, a strong and durable cloth base material is often used.

Preparation of PVC Paste

Once the raw materials are selected, the next step is to prepare the PVC paste. This involves mixing the PVC resin, plasticizers, stabilizers, additives, and other ingredients in a mixer.

• Mixing Process: The mixing process should be carried out under controlled conditions to ensure a homogeneous mixture. The raw materials are first added to the mixer in a specific order. Usually, the PVC resin is added first, followed by the plasticizers, stabilizers, and additives. The mixer is then operated at a certain speed and temperature for a specific period of time to ensure that all the ingredients are thoroughly mixed.
• Viscosity Control: The viscosity of the PVC paste is a crucial parameter that directly affects the processability of the paste. The viscosity is mainly influenced by the type and amount of plasticizers, as well as the mixing conditions. If the viscosity is too high, it will be difficult to process the paste; if the viscosity is too low, the paste may not adhere well to the base material. Therefore, it is necessary to control the viscosity within an appropriate range.

Coating the Base Material

After the PVC paste is prepared, it is time to coat the base material. There are two main methods for coating the base material: direct coating and transfer coating.

• Direct Coating: In the direct coating method, the PVC paste is directly applied to the surface of the base material using a coating machine. The coating machine can be a knife coater, a roller coater, or a spray coater. The thickness of the coating can be adjusted according to the requirements of the final product. After coating, the base material with the PVC paste is sent to an oven for plasticization.
• Transfer Coating: In the transfer coating method, the PVC paste is first coated on a release paper. After plasticization, the PVC layer on the release paper is transferred to the base material. This method can produce PVC synthetic leather with a more uniform thickness and a better surface finish.

Plasticization Process

The plasticization process is a critical step in the production of PVC synthetic leather. It involves heating the coated base material to a certain temperature to make the PVC resin melt and bond with the base material.

• Temperature and Time Control: The plasticization temperature and time are important factors that affect the quality of the PVC synthetic leather. Generally, the plasticization temperature ranges from 100 - 200°C, and the time is usually several minutes. If the temperature is too low or the time is too short, the PVC resin may not be fully plasticized, resulting in poor adhesion between the PVC layer and the base material. If the temperature is too high or the time is too long, the PVC resin may degrade, affecting the mechanical properties and appearance of the leather.
• Oven Types: There are different types of ovens used in the plasticization process, such as hot - air ovens and infrared ovens. Hot - air ovens heat the coated base material by circulating hot air, while infrared ovens use infrared radiation to heat the material. Each type of oven has its own advantages and disadvantages, and the choice depends on the specific production requirements.

Surface Treatment

After the plasticization process, the PVC synthetic leather may undergo surface treatment to improve its appearance and performance.

• Printing and Embossing: Printing and embossing are common surface treatment methods. Printing can add various patterns and colors to the leather, while embossing can create a textured surface, such as a leather - like grain. These treatments can enhance the aesthetic appeal of the PVC synthetic leather and make it more similar to natural leather.
• Coating with Surface Agents: Coating the leather with surface agents can improve its scratch resistance, water resistance, and stain resistance. For example, a layer of polyurethane coating can be applied to the surface of the leather to enhance its durability and easy - cleaning properties.

Quality Control and Finishing

The final step in making PVC synthetic leather is quality control and finishing.

• Quality Control: Quality control is essential to ensure that the PVC synthetic leather meets the required standards. Various tests are carried out, including physical property tests (such as tensile strength, elongation at break, and tear strength), chemical property tests (such as heat resistance, light resistance, and chemical resistance), and appearance tests (such as color uniformity, surface smoothness, and absence of defects).
• Finishing: After passing the quality control tests, the PVC synthetic leather is cut, rolled, and packaged according to the customer's requirements. It is then ready for shipment and use in various applications.

In conclusion, making PVC synthetic leather is a complex process that requires careful selection of raw materials, precise control of processing parameters, and strict quality control. By following these steps, high - quality PVC synthetic leather can be produced to meet the diverse needs of different industries.