Release Paper
In today's industrial production and many commercial application fields, release paper is everywhere. From ensuring the smooth sticking of labels in label printing, to properly protecting precision components in electronic manufacturing, to the key role of demolding in the production process of composite materials, although release paper seems ordinary, it is related to the quality and efficiency of the entire production process. However, facing the wide variety of release paper products on the market, how to accurately judge their quality has become a focus of attention for many companies and users. This is not only related to the final performance and appearance of the product, but also affects the production cost and the reputation of the company. Today, let's take a deep look at the key points and methods of judging the quality of release paper. The quality of release paper can be judged from the following aspects.
Release force refers to the force required to peel the protected material from the release paper. This is one of the most critical indicators for measuring the quality of release paper. Appropriate release force is essential for the normal use of the product. If the release force is too large, the protected material may be difficult to peel off from the release paper during use, and the material may even be damaged. For example, in the label industry, the label may be torn; if the release force is too small, the material will easily fall off when not in use, affecting the storage and transportation of the product.
Test method: You can use a professional release force tester for measurement. Generally, a standard tape (simulating the protected material) is pasted on the release paper, peeled at a certain angle (such as 180° or 90°) and speed, and the required force is recorded. Different application scenarios have different requirements for release force. For example, for ordinary labels, the release force is usually between 3-15g/cm2; while for some protective films of high-precision electronic materials, the release force may be required to be between 1-3g/cm2.
Peeling stability refers to the change of release force during multiple peeling processes. After multiple peelings, the release force of a good quality release paper should remain relatively stable. This is mainly related to the quality of the release agent, the coating process and the surface properties of the paper. If the release agent is not firmly bonded to the paper, or the coating is uneven, the release force may fluctuate significantly after multiple peelings.
Test method: Repeated peeling tests can be performed, such as repeatedly sticking and peeling the release paper with tape for more than 10 times, and observing the changes in the peeling force each time. If the variation in the peeling force each time is within ±10%, it can usually be considered that the peeling stability is good.
The paper strength of release paper includes tensile strength and tear strength. Tensile strength refers to the ability of paper to resist stretching, and tear strength refers to the ability of paper to resist tearing. For application scenarios that need to withstand a certain amount of tension, such as in the production of composite materials, release paper needs to have a higher tensile strength to prevent paper from breaking during processing. For example, when producing large carbon fiber composite materials, if the release paper is not strong enough, it may break during the material laying process, affecting the production process.
Test method: Tensile strength can be tested using a tensile testing machine and operated in accordance with relevant standards. Tear strength can be measured by a tear tester, which is generally tested in different directions of the paper (vertical and horizontal) because the strength of the paper may be different in different directions.
The flatness of the paper directly affects the bonding effect between the release paper and the protected material. If the paper is not flat, it may cause problems such as bubbles and wrinkles after bonding, thus affecting the product quality. The flatness of the paper is related to factors such as papermaking process and water content of the paper. In the printing industry, uneven release paper may cause problems such as blurred printing patterns and decreased registration accuracy.
Inspection method: It can be preliminarily judged by naked eye observation and hand feeling. Place the release paper on a flat table and observe whether its surface has obvious ups and downs and waves. Touch the surface of the paper with your hand to feel whether there are any bumps and bumps. A more accurate method is to use a flatness tester, which can measure the height difference of the paper surface to accurately evaluate the flatness.
The water absorption and air permeability of the release paper will affect the adhesion effect and drying speed of the release agent. If the water absorption of paper is too strong, it may cause excessive penetration of release agent, affecting the uniform distribution of release agent on the surface of paper, thus reducing release performance. If the air permeability is too good, the release agent may dry too quickly, resulting in defects in the coating; if the air permeability is too poor, the release agent may dry too slowly, affecting production efficiency.
Test method: Water absorption can be evaluated by measuring the amount of water absorbed by the paper in a certain period of time, such as testing according to the Cobb method. Air permeability can be measured using an air permeability tester to evaluate the paper's ability to pass gas.
In some applications with high requirements for appearance, such as color labels, protection of decorative materials, etc., the color consistency of release paper is very important. Inconsistent colors may affect the overall aesthetics of the product. At the same time, color uniformity can also reflect the quality of the paper and the stability of the production process from the side.
Inspection method: Put multiple release papers together and compare them under natural light or standard light source to observe whether there is a significant difference in color. A colorimeter can also be used to accurately measure the color difference between release papers. Generally speaking, a △E value (an indicator of color difference) less than 1.5 is considered to have good color consistency.
The cleanliness of the release paper surface is directly related to the quality of the protected material. If there are impurities such as dust, fiber, and oil on the release paper, these impurities may be transferred to the protected material during use, affecting the performance of the material. For example, in the protection of electronic components, impurities may cause short circuits or performance degradation of electronic components.
Inspection method: Carefully observe the surface of the release paper with the naked eye to see if there are visible impurities. In high-demand application scenarios, equipment such as microscopes can also be used for inspection.
Judging the quality of release paper requires a combination of multiple factors. From release performance, paper characteristics to appearance quality, each link is critical. Only by mastering the judgment method can we select high-quality release paper and ensure production and product quality, which is an important guarantee for the high-quality development of the industry.
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