Table of Contents
I. The Difference Between Core Principles and Manufacturing Processes
The base fabric and the PVC coating make up the two primary components of the PVC tarpaulin that we are familiar with. The middle or bottom layer of the fabric is the base fabric, which is a woven fabric composed of high-strength polyester filaments and is frequently referred to as mesh fabric. Polyvinyl chloride, along with plasticizers, fillers, stabilizers, colorants, and other functional additives, make up the PVC coating, which is the tarpaulin’s top and bottom layer. Different manufacturing techniques are needed to produce the PVC coating in various forms, depending on the production process.
Laminated Tarpaulin
The two types of lamination—cold lamination and hot lamination—are based on the temperature differential that occurs during the bonding of the film and mesh. Both types of lamination are quite comparable. In cold lamination, the PVC film is heated in the cylinder of the laminating machine while being bonded to the base fabric at the same time. In hot lamination, one layer of PVC film is first bonded to the base fabric and then to another layer of film while the film is heated in the cylinder of the laminating machine. Higher binding strength between the top and bottom PVC layers is a benefit of hot lamination, but its tensile and tear resistance is comparatively low since the base fabric becomes brittle when heated with the PVC film in the cylinder.Faster lamination speed and the same square weight and thickness are two benefits of cold lamination. Although the top and bottom PVC layers are more easily peeled off due to a weaker adhesive, their tensile and tear resistance is comparatively stronger. A cross-linking agent is not required for either procedure because the base fabric often has rather large mesh apertures that allow contact points between the top and bottom PVC films.
PVC Calendered Film
PVC calendered film is created by combining PVC resin powder and additives in calendering machinery, heating and plasticizing the mixture, and then using rollers to stretch it under pressure. The chemical performance metrics associated with the tarpaulin product’s quality are determined by the PVC film’s composition (formula). The downstream application requirements of the mesh fabric product, such as weather resistance, environmental protection, antistatic properties, antibacterial and mildew-proof properties, flame retardancy, and cold resistance, can be satisfied by utilizing various types of resin powder and additives. Mesh fabrics that are coated and laminated are made from PVC film.
Knife Coated Tarpaulin
The equipment’s primary component is a steel scraper, which is where the term “knife coating” originates. PVC layers are mostly processed by knife coating equipment using coating instead of lamination; PVC film is not used in this process. The slurry is first made in accordance with the specifications, then it is evenly applied to the foundation fabric using a scraper before being heated and plasticized in an oven.
PVC Slurry
PVC slurry is a fluid mixture of resin paste, additives, and pigments that is kept in steel tanks. Its composition is similar to that of calendered film. PVC slurry is a semi-finished raw material used in knife-coated and coated textiles.
As a result, the knife-coating and laminating operations comprise the fabrication of PVC tarpaulins.
II. Methods for Identifying Appearance, Hand feel, and Physical Properties
We can distinguish between knife-coated tarpaulin and laminated tarpaulin by looking at their appearance, feel, and physical properties.
Appearance
There are obvious differences in appearance between knife-coated tarpaulins and laminated tarpaulins. Because the knife-coating process uses a steel scraper to evenly apply the slurry to the surface, the surface of a knife-coated tarpaulin is relatively smooth. However, the laminated process involves bonding two layers of PVC coating together tightly through lamination, so the bottom surface of a laminated tarpaulin will have a noticeable base fabric texture.
Besides these differences, another significant difference is color. If the tarpaulin is produced using a knife-coating process, less sizing agent will remain where the yarns intersect and protrude from the base fabric compared to where they are recessed, resulting in a noticeable color difference. This is especially apparent on brightly colored tarpaulins compared to dark-colored ones.
Hand Feel
Prior to talking about how tarpaulins feel, it’s important to understand what influences their stiffness. Plasticizers are an essential part of PVC calendered film and PVC slurry. The final PVC tarpaulin will be softer if it contains more plasticizers. By varying the amount of plasticizer, we can change the tarpaulin’s stiffness. Because plasticizers must be added during the knife-coating process in order to maintain the PVC slurry’s fluidity. Knife-coated tarpaulins will therefore feel softer under the same conditions as other components.
The bottom surface of a knife-coated tarpaulin is smoother than that of a laminated tarpaulin, and you are unable to feel the texture of the base fabric, which is similar to the difference in appearance. Nevertheless, the feel of laminated tarpaulins is not as smooth as that of a knife-coated tarpaulin, and you can clearly feel the lumps and depressions of the underlying fabric.
Physical Properties
If we are to analyze these two processes from a physical property perspective, we need to understand which aspects of tarpaulin’s physical characteristics are included, and which process produces tarpaulin with better physical parameters and why.
First, after production, we randomly sample from tarpaulin rolls and conduct tests in three areas: tear resistance, tensile strength, and peel strength. Based solely on post-test parameters, the data for knife-scraped PVC tarpaulin is generally slightly lower than that of similarly specified laminated tarpaulin. This is because during the production of knife-scraped PVC tarpaulin, each layer of coating must undergo high-temperature oven curing. However, excessive heating can degrade the overall performance of the tarpaulin. High temperatures cause the plasticizers in PVC to gradually volatilize, making the tarpaulin lose its softness and become brittle; simultaneously, repeated heating and cooling weaken the bonding force between layers, reducing peel strength.
Additionally, the base fabric is prone to thermal shrinkage or deformation under prolonged high temperatures, leading to poorer tear and tensile performance. In contrast, laminated tarpaulin requires only a single hot-pressing process, resulting in lighter thermal aging. Consequently, it often exhibits superior physical properties (such as tensile and peel strength) compared to knife-scraped tarpaulin. Simply put, the excessive baking of knife-scraped tarpaulin is like repeatedly heating bread—it may look unchanged, but its internal flexibility is significantly compromised.
III. Which Tarpaulin has Better Durability?
Knife-coated tarpaulin is made from PVC paste resin. During the manufacturing process, this raw material is molded and plasticized in one step. In other words, when the PVC paste is scraped onto the foundation fabric, it is not completely created. Rather, it goes through a high-temperature plasticization in the oven, which enables the PVC molecules to completely combine with the foundation fabric fibers to create an overall structure that is dense, consistent, and securely linked.
Pre-plasticized PVC material, which has already gone through one plasticization step during production, is the tarpaulin that is utilized. In order to bind with the foundation fabric, it then goes through a second heating or hot-pressing step during the lamination process, effectively going through two plasticization procedures. The stability and flexibility of PVC are diminished by repeated heating, which breaks part of the molecular chains in the polymer. Additionally, there is comparatively less adherence between the coating and the base fabric since the bonding during this second plasticization depends more on thermal adhesion than on molecular-level penetration and fusion.
As a result, knife-coated tarpaulin undergoes a single plasticizing process that not only strengthens the bond between the coating and the base fabric but also makes the PVC molecular structure more stable and less susceptible to aging from time, temperature, or UV radiation. In contrast, laminated tarpaulin undergoes two plasticizing processes, which partially degrades the molecular structure, increasing the likelihood of issues like surface cracking, delamination, and fading over time.
IV. Application Scenarios and How to Make the Right Choice
There isn’t much of a difference between laminated and knife-coated tarpaulin in real-world applications. The only exceptions are materials that need to be extremely airtight, like air-tight or liquid-tank textiles, which require laminated tarpaulin.
Because laminated tarpaulin has inherent structural advantages, these goods are limited to using the lamination technique. In order to reduce heat exposure and maintain the base cloth’s original strength, stiffness, and dimensional stability, it is created by gluing many layers of base fabric and PVC film together at comparatively low temperatures. The material used to make bag textiles must be sturdy, supportive, and able to hold its shape whether bent, compressed, or loaded. Laminated fabric is the best option for bag manufacturing because of its layered structure, which improves shaping performance and wrinkle resistance.
Furthermore, laminated tarpaulin is better suited for items that need superior sealing capability, such as liquid tanks or airtight fabrics. Stronger, pore-free sealing lines can be formed by hot-air and high-frequency welding thanks to the even, solid PVC layer of laminated fabric and the smooth, continuous bonding surfaces between layers. This guarantees that even in situations of high pressure, high temperature, or prolonged storage, liquids or air won’t leak. Knife-coated fabrics, on the other hand, are subjected to greater temperatures and repeated heating during the blade-coating and oven curing processes, which may result in minor internal stress or deformation in the base fabric and a somewhat poorer sealing ability. For applications needing extreme airtightness or liquid tightness, knife-coated textiles are therefore not advised.
In conclusion, laminated tarpaulin is a superior option for bags, airtight textiles, and liquid-tank materials that require high rigidity, sealing performance, and dependability, whereas knife-coated tarpaulin is more appropriate for common outdoor covers, advertising banners, and truck canopies.
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I am Felicia. I have been working in the PVC tarpaulin industry at Haining Lona Coated Material Co., Ltd. for nearly 10 years.With nearly 20 years of experience in the textile foreign trade industry. I am confident that my professional expertise and high-quality products will win your trust.