Vacuum Pumping Phases for PET Container Coating

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Solution Overview

Problem

Simultaneous pumping of a container and its cavity to achieve vacuum for internal coating deposition is challenging due to uneven pressure reduction, leading to mechanical stress and potential container collapse, as PET containers are not designed to withstand significant pressure differences.

Innovation Solution

Implementing a method where the external and internal vacuum lines are pumped independently, with an external pumping phase reducing cavity pressure and an internal pumping phase reducing container pressure, allowing for controlled pressure reduction and preventing container collapse.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If simultaneous pumping from cavity and container is performed, then vacuum is achieved for coating deposition, but pressure difference causes container collapse

Engineering Contradiction:

Improvevacuum achievementVSAvoidcontainer mechanical strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The pumping process is segmented into three distinct phases: external pumping phase (cavity only), intermediate pumping phase (both cavity and container), and internal pumping phase (container only). This segmentation allows controlled pressure reduction in each zone, preventing excessive pressure differential that would cause container collapse while still achieving the required vacuum levels for coating deposition.

Inventive Principle:

Principle #1Segmentation

2Strength

If container wall thickness is increased to prevent collapse, then mechanical strength is improved, but weight and cost increase

Engineering Contradiction:

Improvecontainer mechanical strengthVSAvoidcontainer weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent replaces the mechanical solution (increasing wall thickness) with a process control solution (sequenced pumping phases). By controlling the vacuum application sequence, the system achieves the required mechanical strength without physically modifying the container structure, thereby avoiding increased weight and cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Strength

If container shape is modified to increase strength, then mechanical strength is improved, but design freedom is reduced

Engineering Contradiction:

Improvecontainer mechanical strengthVSAvoidcontainer shape freedom

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The patent replaces the geometric design solution (modifying container shape) with a process control solution (sequenced pumping phases). This allows standard container shapes to be used without modification, preserving design freedom and versatility while still achieving the required mechanical strength through controlled vacuum application.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Productivity

If pressure reduction rate is increased to achieve vacuum faster, then productivity is improved, but pressure difference causes container collapse

Engineering Contradiction:

Improvevacuum achievement speedVSAvoidcontainer mechanical strength

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The pumping process is divided into phases with different speed characteristics. The external pumping phase can proceed rapidly to establish cavity vacuum, followed by the intermediate phase that balances cavity and container pressure reduction, and finally the internal pumping phase that achieves the required container vacuum. This segmented approach maintains high overall productivity while preventing excessive pressure differential at any moment.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method allows for efficient and controlled pressure reduction in both the cavity and container, preventing mechanical stress and enabling successful treatment without increasing container weight or constraining its shape.

Implementation Method 1

the pumping circuit produces a pressure reduction inside the cavity to a set value called the final external value, and a pressure reduction in the container to a set value called the final internal value

Methodology Applied

Scientific EffectVacuum pumping: Pump

Implementation Method 2

a precursor fluid (for example based on acetylene in the case of the production of a carbon-containing coating, or an organosilicon-containing compound in the case of a silica-based deposit) is injected into the container and subjected to the action of microwaves so that it passes to the plasma state and produces a barrier deposit on the internal walls of the container

Methodology Applied

Scientific EffectMicrowave plasma generation: Plasma

Data Source

PatentUS7838071B2Container-treatment method comprising vacuum pumping phases, and machine for implementing same

Publication Date: 2010.11.23 SIDEL PARTICIPATIONS SAS

AI summary

A container-treatment method, of the type in which the container (12) is disposed inside a chamber (16) which defines a cavity (18) outside the container (12) and which is connected to a Vacuum pumping circuit (50), the interior of the container (12) being connected to the pumping circuit (50). The method includes a preliminary pumping step (E1) which is followed by a treatment step (E2). The preliminary step (E1) includes the following successive phases, namely: an external pumping phase (P1) which produces a drop in the pressure inside the cavity (18) only; and an internal pumping phase (P2) which produces a drop in the pressure inside the container (12) only. A machine used to implement the method is also disclosed.