Repulpable Paper Straps via Non-Twisted Pultrusion

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Solution Overview

Problem

Conventional paper straps for bundling pulp bales have limited strength and hinder repulpability due to twisting and folding processes, which increase manufacturing costs and require additional materials like synthetic fibers, compromising machine runnability and repulpability.

Innovation Solution

A method involving pultrusion technology to form non-twisted paper straps by directing paper strips through a series of dies, eliminating the need for twisting and folding, and using water-soluble adhesives to enhance strength and flexibility, while maintaining repulpability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If paper strips are twisted or folded to form conventional paper straps, then the straps can maintain their shape and provide bundling function, but the tensile strength is reduced and repulpability is hindered

Engineering Contradiction:

Improvetensile strengthVSAvoidmanufacturing complexity

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

Instead of twisting or folding paper strips to form straps (conventional approach), the patent inverts the process by pultruding paper strips through a die to form a consolidated strap structure. This inversion eliminates the need for twisting while maintaining shape integrity and improving tensile strength by aligning fibers in the direction of stress.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the physical state and structural parameters of paper strips during pultrusion. The paper strips are fed through a heated die where they are consolidated under heat and pressure, transforming them from separate strips into a unified strap with enhanced mechanical properties and improved repulpability compared to twisted conventional straps.

Inventive Principle:

Principle #35Parameter changes

2Strength

If synthetic fibers are added to improve tensile strength of paper straps, then the strength increases, but repulpability and machine runnability are compromised

Engineering Contradiction:

Improvetensile strengthVSAvoidrepulpability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent achieves improved tensile strength by changing the structural parameters of pure paper strips through pultrusion consolidation, eliminating the need for synthetic fiber additives. The heat and pressure applied during pultrusion create strong inter-fiber bonding while maintaining the natural repulpability of cellulose fibers.

Inventive Principle:

Principle #35Parameter changes

3Shape

If tight twisting is applied to retain cylindrical shape of paper straps, then the shape is maintained, but manufacturing time and cost increase

Engineering Contradiction:

Improvecylindrical shape retentionVSAvoidmanufacturing efficiency

Core Design Contradiction:

ShapeVSProductivity

Solution Approach 1:

The patent inverts the conventional twisting process by using pultrusion to directly form the cylindrical strap shape during extrusion. This eliminates the need for subsequent twisting operations while maintaining shape integrity, significantly improving manufacturing efficiency.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The pultrusion die performs the shape-forming action preliminarily during the extrusion process itself, rather than requiring a separate twisting step after strap formation. This preliminary shaping action integrates multiple functions into one operation, reducing manufacturing time and cost.

Inventive Principle:

Principle #10Preliminary action

4Ease of manufacture

If multiple twists and folds are applied to form paper straps, then the strap structure is created, but fiber orientation is continually changed resulting in strength loss

Engineering Contradiction:

Improvestrap formation capabilityVSAvoidtensile strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent inverts the conventional approach of twisting and folding by using linear pultrusion to form straps. This maintains consistent fiber orientation along the strap length, preserving tensile strength while still achieving the required strap structure through the die geometry.

Inventive Principle:

Principle #13The other way round (Inversion)

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 produces paper straps with improved tensile strength and cost-effectiveness, maintaining repulpability and reducing manufacturing complexities, as evidenced by increased ultimate tensile strength and efficient machine runnability.

Implementation Method 1

a first pultrusion string die to form intermediate strings

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 2

using water-soluble adhesives to enhance strength and flexibility

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS11434608B2Methods for making repulpable paper strings and straps through pultrusion process and related devices for the same

Publication Date: 2022.09.06 ENTERPRISES INTERNATIONAL INC

AI summary

A method for forming paper straps is provided. The method may include providing a paper strip from a base sheet and directing the paper strip through a first die to form an intermediate string. The method may further include directing the intermediate string from the first die through a second die, the intermediate string exiting the second die in a substantially non-twisted state. Related apparatuses and devices to form paper straps are also provided.