Two key aspects for quality control of blown film color masterbatches 

Blow-molding color masterbatches are widely used for coloring plastic packaging films, agricultural films, garbage bags, shopping bags, and other blow-molded products. The blow-molding process has high requirements for the dispersibility, heat resistance, and filtration performance of color masterbatches. The quality of color masterbatches directly affects the appearance quality of the film surface and the stability of blow-molding production. As a purchaser, what you care about is not only whether the color is accurate, but also whether there are crystal points on the film surface after the machine is put into operation and whether there is a risk of film rupture during blow-molding. Below, from the production perspective, we will introduce how we control these two aspects. 

1. Dispersion and Filtration Performance: Ensuring the Prevention of Crystallization Points and Net Blockage 

In the film blowing process, the dispersion property of the color masterbatch is the key factor determining the quality of the film surface. 

Pigment dispersion control: If there are agglomerated particles of pigments in the color masterbatch, during the film blowing process, these agglomerates will form "crystalline points" or "white spots" on the film surface, which not only affect the appearance but also may cause the film to tear at the crystalline points when subjected to force. We adopt twin-screw mixing and an efficient dispersion system to ensure the uniform distribution of pigments in the carrier. During the production process, samples are taken at regular intervals and pressed into tablets, and visible color spots are observed on the light-transmitting platform. Lu'an Qingsong Color Masterbatch Co., Ltd. specializes in the production of polypropylene (PP) color masterbatches, non-woven fabric color masterbatches, plastic film blowing color masterbatches, etc. It has conventional detection methods for dispersion performance. 

Filtering performance: The color masterbatches used for film blowing need to undergo more precise filtration to remove any possible agglomerated particles or impurities. We are equipped with appropriate mesh sizes of filters to reduce the risk of crystal points and clogged filters caused by impurities in the masterbatches. 

II. Heat Resistance and Batch Stability: Essential for Smooth Film Extrusion 

The processing temperature for film blowing is usually between 160℃ and 220℃. The heat resistance and batch stability of the color masterbatch directly affect the continuity of film blowing production and the quality of the finished products. 

Heat resistance: If the pigments or additives in the color masterbatch are unstable at the blown film temperature, they may decompose and produce gas (resulting in bubbles on the film surface) or form carbonates (causing black spots on the film surface). We select a pigment and additive system with heat resistance matching the blown film process to avoid film surface defects caused by thermal decomposition. 

Batch stability: Blown film color masterbatches are usually purchased in batches. The stability of color and dispersion effect between batches directly affects the consistency of the film surface appearance. We keep samples and color charts for each batch. During the production of the next batch, we will compare the color and tablet dispersion effect with the samples from the previous batch to ensure no significant changes. 

Summary and Selection Suggestions 

When purchasing blown film color masterbatches, it is recommended to confirm the following steps: 

Let's start with the dispersion aspect: Request samples of the color masterbatch and conduct a small-scale trial on your blown film equipment. Observe if there are any crystal or color spots on the film surface. This is a direct way to assess the quality of the color masterbatch. 

Re-test heat resistance: Conduct pilot production at your actual film blowing temperature and observe whether any bubbles or black spots appear on the film surface. 

Final confirmation of batch consistency: The supplier is required to provide color swatches from multiple recent batches for comparison, in order to assess the stability of the color and dispersion effect. 

Luan Qingsong Masterbatch Co., Ltd. specializes in the production of polypropylene color masterbatches, non-woven fabric color masterbatches, plastic blown film color masterbatches, hydrophilic masterbatches, flame-retardant masterbatches, etc. We welcome sample requests for testing and communication of process requirements. 

Official website: www.qssml.com