In today’s packaging industry, PET (Polyethylene Terephthalate) has become widely used for its excellent properties. PET preforms, as a critical intermediate product in PET bottle manufacturing, play an essential role in determining both production efficiency and final product quality. The quality of PET preforms impacts the transparency, pressure resistance, impact strength, and overall appearance of the finished bottles. If you’re looking for insights into PET preforms, this blog will provide practical knowledge on preform types, common specifications, and key considerations in the injection molding process.
1. What Are PET Preforms?
PET preforms, also known as PET bottle, are semi-finished products that can be blow-molded into various shapes and purposes of PET bottles. They are widely used in industries like bottled water, carbonated beverages, edible oils, cosmetics, and pharmaceuticals. Choosing the right type of preform and maintaining strict control over the production process are crucial for creating high-quality PET bottles.
2. Common Types of PET Preforms
Based on design requirements, PET preforms can be generally categorized into the following types:
– Standard Beverage PET Preforms
These preforms are commonly used to produce mineral water bottles, carbonated beverage bottles, etc. They typically require high transparency and durability to meet consumer demands for aesthetics and pressure resistance.
– PET Preforms for Oil or Sauce Bottles
Preforms for oil, soy sauce, and other liquids often specialized designs to ensure excellent sealing performance and resistance to corrosion. These preforms may have slightly thicker walls for enhanced strength and stability during storage with transportation.
– Cosmetic Container PET Preforms
The cosmetics industry places a high emphasis on packaging design and appearance. Thus, these preforms need to combine elegant designs, high gloss, and diverse color options while also meeting storage needs such as moisture resistance and leak prevention.
– Pharmaceutical Packaging PET Preforms
Pharmaceutical-grade PET preforms must meet stringent hygiene standards and offer excellent sealing and UV protection to ensure the safety and effectiveness of medicines. Moreover, these preforms often come with specific designs, such as distinct colors, to differentiate between drug categories.
– Custom PET Preforms
This category caters to specialized market demands, such as detergent bottles, pesticide bottles, or small reagent containers. These preforms are typically tailored to unique shapes and specifications based on individual requirements.
3. Key Considerations in the PET Preform Injection Molding Process
The production of PET preforms involves a sophisticated injection molding process. Below are several critical factors to consider during production:
– Raw Material Selection
The quality of PET material directly determines the performance of the preform. The raw materials should meet food-grade or industrial standards, free from impurities or contaminants. Additionally, the material’s intrinsic viscosity and molecular weight must be suitable for injection molding.
– Drying Treatment
PET is highly hygroscopic, so it must be dried thoroughly before injection molding. Insufficient drying can result in defects like bubbles, white spots, or compromised mechanical properties. Typically, PET requires drying at around 160°C for at least 4 hours.
– Accurate Mold Temperature Control
Mold temperature control is critical for ensuring the quality of the preforms. Too low a mold temperature can lead to rough surfaces, while too high a temperature may cause deformation. Real-time monitoring and adjustments are necessary during production.
– Injection Parameters Configuration
Precise setting of injection parameters, such as temperature, pressure, and speed, is crucial for maintaining consistency in the preforms. Stable injection pressure is needed to avoid uneven wall thickness.
– Cooling Time and Speed
Insufficient cooling time may cause deformation or warping, while excessive cooling prolongs the production cycle, reducing efficiency. Optimizing the cooling process ensures balanced production efficiency and product quality.
– Regular Inspection and Adjustment
Regular inspection of dimensions, wall thickness, and transparency ensures the preforms meet desired specifications. Any issues detected should prompt immediate adjustment of equipment or process parameters to prevent further defects.
4. Common Specifications of PET Preforms
When selecting PET preforms, specifications—such as thread standards, weight, and dimensions—are important factors to consider. Below are some common PET preform specifications widely used in the industry:
PCO 1810
- Application: Often used for carbonated beverage bottles.
- Features: Larger neck diameter with strong sealing capabilities, suitable for high-pressure environments.
- Thread Specification: 28mm thread
- Weight Range: 10g–40g (depending on bottle capacity.
PCO 1881
- Application: Lightweight preforms for carbonated beverages and water bottles.
- Features: A lighter alternative to PCO 1810, designed for energy-saving and sustainability needs.
- Thread Specification: 28mm thread
- Weight Range: 8g–30g
29/25
- Application: Non-carbonated beverage bottles, such as juice and tea.
- Features: Slightly smaller neck diameter than PCO 1810, ideal for low-pressure products.
- Thread Specification: 29mm diameter, with a narrower top section.
38mm
- Application: Containers for edible oils and dairy products.
- Features: Wider neck diameter for easy pouring and food-grade sealing requirements.
- Thread Specification: 38mm wide-neck
- Weight Range: 20g–50g
48mm
- Application: Large-capacity household packaging, such as bulk water or sauces.
- Features: Larger neck diameter for ease of use, commonly found in gallon-size or multipurpose containers.
26/22
- Application: Small beverage bottles and reagent containers.
- Features: Narrow neck diameter, suitable for portable or compact packaging.
- Thread Specification: 26mm outer diameter, narrowing to 22mm at the threaded section.
When choosing the specification of a PET preform, it’s important to consider its intended use, filling conditions, transportation methods, and the overall bottle design.
If you have any questions about PET preform injection molding or mold design, feel free to contact us! We look forward to providing professional solutions tailored to your needs.
We hope this guide has helped you better understand PET preforms, and we look forward to collaborating with you!
Contact: Jenny@tigermould.com