Plastic Bag Heat Sealing With Micro-Protrusions to Prevent Edge Break

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Solution Overview

Problem

Existing thermal bonding methods for plastic bags face challenges in achieving hermetic sealing while preventing bag rupture and ensuring adhesive strength that asymptotically approaches the breaking force of the material, often resulting in edge breaks and pinhole formation due to uneven heat distribution and excessive sealant overflow.

Innovation Solution

A thermal bonding method using a heat bar with a microscopic semi-circular or trapezoidal protrusion to inject melted sealants along the edge, forming a mold adhesion strip, which suppresses sealant overflow and enhances cohesive adhesion, thereby preventing bag rupture and achieving strong hermetic sealing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If thermal bonding is performed using conventional heat bars, then hermetic sealing is achieved, but bag rupture occurs due to edge break and pinhole formation

Engineering Contradiction:

Improvehermetic sealingVSAvoidbag rupture resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The heat bar surface is designed with localized microscopic protrusions (semi-circular or trapezoidal shapes) at specific positions to control sealant melting and injection. This local structural modification concentrates thermal energy and sealant flow at precise locations, preventing random overflow and edge break while maintaining hermetic sealing integrity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The heat bar protrusions are pre-formed with specific dimensions and geometries before thermal bonding. These pre-configured microscopic structures guide the sealant melting and injection process, ensuring that sealant is injected in controlled amounts along the edge before the bonding process completes, thereby preventing post-bonding edge break and pinhole formation.

Inventive Principle:

Principle #10Preliminary action

2Strength

If sealant is melted and injected to form mold adhesion strip, then adhesive strength approaches breaking force, but excessive sealant overflow causes edge break

Engineering Contradiction:

Improveadhesive strengthVSAvoidsealant overflow

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The microscopic protrusions on the heat bar are designed with specific dimensional parameters (semi-circular or trapezoidal shapes with controlled sizes) that regulate the amount of sealant melted and injected. By precisely controlling these geometric parameters, the system achieves optimal sealant flow - enough to form strong mold adhesion but not so much as to cause overflow and edge break.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The microscopic protrusions act as intermediary structures between the heat bar and the sealant. These protrusions mediate the thermal energy transfer and sealant flow, converting excessive thermal energy into controlled sealant injection along the edge rather than uncontrolled overflow. The protrusions serve as a buffer that regulates the interaction between heat, sealant, and the bonding interface.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If heating temperature is increased to achieve cohesive adhesion, then adhesive strength improves, but edge break and pinhole formation increase

Engineering Contradiction:

Improvecohesive adhesionVSAvoidedge break

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The heating surface is segmented into multiple microscopic protrusion elements distributed across the heat bar. This segmentation allows thermal energy to be applied in distributed, controlled points rather than uniformly across the entire surface. The protrusions create localized heating zones that achieve cohesive adhesion through concentrated thermal energy while the distributed nature prevents excessive heat accumulation that would cause edge break and pinhole formation.

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

The method effectively prevents bag rupture and ensures adhesive strength that closely matches the material's breaking force, reducing plastic material usage and improving hermetic sealing reliability.

Implementation Method 1

pressing heat-generating metal bodies against bonding outer surfaces or using internal heat generation in a material, which is caused by an electromagnetic wave or an ultrasonic wave

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the sealant that has been melted at a temperature within a temperature zone for cohesive adhesion

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS20260109504A1Thermal bonding method for plastic bag and method of manufacturing plastic bag

Publication Date: 2026.04.23 HISHINUMA KAZUO

AI summary

Provided is a thermal bonding method for a plastic bag, comprising: heat-sealing a heat sealing material interposed between a pair of heating bodies, wherein one of the pair of healing bodies has a microscopic linear protrusion having a semi-circular or trapezoidal sectional shape, and wherein the heated linear protrusion is pressed against a sealant of the heat sealing material to inject the sealant that has been melted at a temperature within a temperature zone for cohesive adhesion in a strip-like shape along a side edge of the linear protrusion so as to form a mold adhesion strip.