1. Physical properties

Thickness uniformity
Importance: PET sheets with uniform thickness can ensure uniform pressure distribution during printing, avoiding problems such as false printing and uneven color. For high-precision printing, such as small text and patterns on labels and packaging, thickness uniformity is particularly critical.
Testing method: You can use a micrometer to measure the thickness of the PET sheet at different positions and observe its deviation range. Generally speaking, the thickness deviation of high-quality PET sheets should be controlled within a small range, such as ±0.005mm.
Stiffness
Importance: Stiffness determines the stability of PET sheets during printing and subsequent processing. Sheets with high stiffness are not easy to deform, which is convenient for conveying and positioning of the printing machine, and can also ensure that the printed products maintain a good shape. Stiffness is an important consideration, especially when making printed products such as packaging boxes and display racks that require a certain amount of support.
Testing method: Measure the PET sheet with a stiffness tester and select sheets with appropriate stiffness according to different application requirements. For example, for large display boards, PET sheets with high stiffness are required to ensure that they can stand on their own and are not easy to bend.

Transparency

Importance: If the printed material requires high transparency to display the internal products or achieve a specific visual effect, the transparency of the PET sheet is crucial. High-transparency PET sheets can make the printed patterns clearer and more vivid, while not affecting the effect of observing objects through the sheet.
Detection method: Use a transparency tester or observe with the naked eye to compare the transparency of different PET sheets. High-quality PET sheets should have a high transmittance, generally above 90%.

2. Chemical properties

Chemical corrosion resistance

Importance: In some special application scenarios, such as printing chemical reagent bottle labels, cosmetic packaging, etc., PET sheets need to have good chemical corrosion resistance to prevent reactions with substances in the packaging and affect product quality and safety.
Detection method: PET sheets can be immersed in different chemical reagents to observe changes in their appearance and performance. For example, after soaking the sheet in acid or alkali solution for a certain period of time, check whether there is discoloration, deformation, dissolution, etc.

Surface tension

Importance: Surface tension affects the adhesion of ink on PET sheets. Appropriate surface tension can ensure that the ink adheres firmly to the surface of the sheet and is not easy to fall off. For printed products that need to be processed later or used in harsh environments, good ink adhesion is essential.
Testing method: Use a surface tension tester to measure the surface tension of PET sheets. Generally speaking, the surface tension of PET sheets after surface treatment should reach a certain value, such as 38 dynes/cm or more, to ensure good adhesion of ink.

III. Environmental performance

Recyclability

Importance: With the improvement of environmental awareness, recyclable PET sheets are becoming more and more popular. Choosing recyclable sheets not only helps to reduce the impact on the environment, but also meets the requirements of sustainable development. For some companies and brands that focus on environmental protection, using recyclable PET sheets to print packaging and promotional materials can enhance their sense of social responsibility.
Identification method: Check the product description or consult the supplier to understand the recycling logo and recycling method of PET sheets. Some PET sheets may be marked with the word “recyclable” and provide corresponding recycling channel information.
Low VOC emissions

Importance: During the printing process, the sheets may release volatile organic compounds (VOCs), which are harmful to the environment and human health. Choosing PET sheets with low VOC emissions can reduce air pollution in the printing workshop and improve the quality of the working environment.
Testing method: Require suppliers to provide VOC test reports for sheets to ensure that their emissions meet environmental standards. At the same time, you can choose to use environmentally friendly inks and printing processes to further reduce VOC emissions.

IV. Suppliers

Product quality stability

Importance: Stable product quality is the basis for ensuring printing quality. Choosing a supplier with a good quality control system can ensure that the performance of each batch of PET sheets is consistent and reduce printing problems caused by fluctuations in sheet quality.
Evaluation method: Understand the supplier’s production process, quality inspection process, and quality management system certification. You can ask the supplier to provide samples for testing and compare them with other suppliers’ products. At the same time, refer to other customers’ comments and feedback to understand the supplier’s reputation and product quality stability.
Technical support and service

Importance: When choosing PET sheets, the supplier’s technical support and service are also important. They can provide professional advice and solutions to help customers choose the most suitable sheets and solve problems encountered during printing.
Investigation content: Understand whether the supplier provides technical consultation, training and after-sales service. For example, whether the supplier can provide customized sheet solutions according to the specific needs of customers, and whether there are professional technicians to assist in solving technical problems in printing.