Why PP polypropylene can't stick firmly

The main reasons for PP's poor adhesion are its low surface energy, high chemical inertness, low surface roughness, high crystallinity, and low heat deflection temperature. These factors combine to make it difficult for adhesives to effectively adhere and cure. The following is a breakdown of the specific reasons:

Low surface energy: PP plastic's low surface energy makes it difficult to wet, making it difficult for adhesives to form good contact with the adhesive. This prevents the adhesive from fully penetrating and diffusing into the PP plastic surface, thus affecting the strength and reliability of the bond.

High chemical inertness: PP plastic is highly chemically inert, making its surface less reactive to other substances. This makes it difficult for conventional adhesives to form a strong bond with PP plastic, as adhesives typically rely on chemical reactions with the material's surface to form a bond.

Low surface roughness: PP plastic's surface is typically smooth and lacks sufficient surface roughness. This makes it difficult for adhesives to form good adhesion, as a rough surface increases the contact area and mechanical engagement between the adhesive and the material. High crystallinity: PP plastic is a semi-crystalline material. Its high crystallinity results in a high number of crystalline regions within the material. These regions interact weakly with the adhesive, further impacting bonding.
Low heat deformation temperature: PP plastic has a relatively low heat deformation temperature. Conventional adhesives, when subjected to high temperatures during the curing process, may cause deformation or melting of the PP plastic, thus affecting bonding quality.

You can use the excellent room-temperature slow-drying glue KN-300a and quick-drying glues (such as 460, 490, 601, and 603) in combination with silicone treatment agents K770-5 or CL-16-5 to achieve rapid bonding, making them ideal for assembly line operations.

In addition to quickly bonding silicone PP water bottles, these adhesives can also be used on other silicone products, toys, cosmetics, daily necessities, crafts, and accessories, demonstrating their wide applicability.