There is a peculiar smell after the plastic granulator is granulated, what should I do?

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What are the common causes of peculiar smell after granulation by plastic granulator?

  1. The materials are relatively complex.

  2. Materials degrade after multiple processing.

  3. Decomposition of small molecule materials in materials.

  4. Sometimes materials with mixed moisture have a strong effect on accelerating degradation. Pay more attention to the above and the processing temperature should not be too high.

A brief analysis of the causes of odor problems in PET bottled drinking water


The odor problem of PET bottled drinking water has gradually attracted the attention of consumers. Although it does not affect hygiene and health, it still requires sufficient attention from manufacturing companies, logistics and sales terminal companies.

PET bottled water consists of water, a PET bottle and a plastic cap. Water is colorless and odorless, with slightly odorous components dissolved in it, which will produce an unpleasant taste when consumed.

PET bottles are made of food-grade PET material. PET material, whose scientific name is polyethylene terephthalate, is colorless and odorless at room temperature. It is widely used in the fields of beverages, food, and edible oils.

Plastic lids are usually made of food-grade HDPE material. The scientific name is high-density polyethylene, which is colorless and odorless at room temperature. It is widely used in the fields of beverages, food, and edible oils.

So, where does the odor in water come from? After a lot of research and testing, people came to the conclusion that the odor in water comes from the packaging materials. The main manifestations are:

The packaging material's own taste: Although the packaging material is odorless at room temperature, when the temperature is higher than 38°C for a long time, the small molecular substances in the packaging material are prone to volatilize and migrate into the water, causing odor.

PET materials and HDPE materials composed of polymers are very sensitive to temperature. Generally, the higher the temperature, the greater the smell. Since some medium and low molecular substances remain in the polymer, at high temperatures, it volatilizes more odor than the polymer. Avoid transportation and storage under high temperature conditions to effectively avoid the generation of odor.

Under the irradiation of ultraviolet rays, some low-molecular substances will be decomposed and produce odor.

The packaging materials have been added with anti-ultraviolet substances, but under the conditions of exposure to the sun, some medium and low molecular chain end group substances remain in the polymer, which are easily activated and produce trace amounts of degradation products, which dissolve in water and produce odor. If high temperature is added, the odor will be more obvious. Direct sunlight should be avoided, and transportation and storage at a suitable temperature can effectively avoid the generation of odor.

Degradation of additives in bottle cap raw materials

The main purpose of adding lubricant is to improve the opening performance of the bottle cap and make it easier for consumers to drink; to add a release agent to facilitate the smooth release of the cap from the mold when making the cap; to add color masterbatch to change the color of the cap and diversify the appearance of the product.

These additives usually contain unsaturated fatty amides, in which the double bond C=C structure is easily oxidized. If exposed to ultraviolet light, high temperature, and ozone, this double bond can be opened to form a degraded mixture: saturated and unsaturated fatty acids, acetaldehyde, carboxylic acids, and hydroxides, etc., which can easily dissolve into water and produce different tastes. and odor.

Choosing additives that match the production process can effectively avoid the generation of volatile odorous mixtures. Sincera, a lubricant developed by GRACE in the United States, does not degrade under ultraviolet rays, ozone and high temCompression molding process: Using a compression molding machine to cover the lid is a new technology that has emerged in recent years. It does not require additives (except color masterbatch). The processing temperature is controlled at 160℃-170℃, which will not cause chemical changes in the material.peratures. It has been commercially applied in European and American markets.

Odor residue from the cap making process

The materials used to make the caps are added with additives such as lubricants. Cap making includes processes such as heating and high-speed mechanical stirring. The odor generated due to the processing process remains in the lid and will eventually migrate into the water.

There are usually two processes for making caps: injection molding and compression molding.

Injection molding process: Using an injection molding machine to cover the lid is a traditional method. Additives must be used, and the temperature is between 240°C and 280°C. At high temperatures, the materials will undergo some chemical changes and produce odor.

An effective way to reduce the odor produced by lid making is to use as few additives as possible in the materials and lower the processing temperature. Many well-known international companies use the compression molding process to make lids, and they believe this is an effective method.