Paper Substrate Sizing Composition for Inkjet Print Density

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Solution Overview

Problem

Conventional paper substrates for inkjet printing face challenges in achieving high print density, sharpness, low HST (Hercules Sizing Test Value), and reduced color-to-color bleed while maintaining high brightness and image dry time.

Innovation Solution

A sizing composition is applied to paper substrates, comprising pigments like calcium carbonate and binders such as polyvinyl alcohol, along with nitrogen-containing organic species and optical brightening agents, to enhance print quality and reduce HST, with specific ratios and amounts optimizing the composition for improved performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional paper substrates are used for inkjet printing, then basic printing functionality is achieved, but print density, sharpness, and waterfastness are insufficient

Engineering Contradiction:

Improveprint density and sharpnessVSAvoidwaterfastness and color-to-color bleed

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies a composite sizing composition containing multiple components including inorganic pigments (calcium carbonate), organic binders (polyvinyl alcohol), nitrogen-containing compounds (polydiallyldimethylammonium chloride), and optical brightening agents. This composite formulation simultaneously improves print density, sharpness, and waterfastness while reducing color-to-color bleed, resolving the contradiction between manufacturing precision and reliability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical and physical parameters of the paper substrate surface by controlling the concentration ratios of components in the sizing composition (e.g., 10-50 wt% pigment, 5-40 wt% binder, 1-20 wt% nitrogen-containing compound) and processing conditions (drying temperature, application method). These parameter changes enable simultaneous improvement of print quality metrics and waterfastness properties.

Inventive Principle:

Principle #35Parameter changes

2Loss of time

If HST is reduced to improve image dry time, then printing speed is improved, but print density and sharpness may deteriorate

Engineering Contradiction:

Improveimage dry timeVSAvoidprint density and sharpness

Core Design Contradiction:

Loss of timeVSManufacturing precision

Solution Approach 1:

The patent reduces HST to less than 10 seconds (preferably less than 5 seconds) by optimizing the sizing composition parameters, specifically the balance between binder content (5-40 wt%) and pigment content (10-50 wt%), along with nitrogen-containing compound concentration (1-20 wt%). This parameter optimization achieves rapid image drying while maintaining print density greater than 1.0 and sharpness, resolving the time-quality contradiction.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The sizing composition acts as an intermediary layer between the paper substrate and ink, containing binders that facilitate rapid water evaporation (reducing HST) while pigments and optical brightening agents maintain print density and sharpness. The nitrogen-containing compounds further mediate by controlling surface properties to achieve low HST without compromising print quality.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Illumination intensity

If brightness is increased to improve visual quality, then aesthetic appearance is enhanced, but color-to-color bleed increases

Engineering Contradiction:

ImprovebrightnessVSAvoidcolor-to-color bleed

Core Design Contradiction:

Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The patent uses a composite sizing composition where optical brightening agents (0.1-10 wt%) enhance brightness by fluorescent emission, while inorganic pigments like calcium carbonate (10-50 wt%) and binders (5-40 wt%) form a matrix that prevents ink migration. The nitrogen-containing compounds (1-20 wt%) further control surface properties to reduce capillary action. This composite approach achieves high brightness (greater than 80% GE brightness) while minimizing color-to-color bleed.

Inventive Principle:

Principle #40Composite materials

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 solution significantly improves print density, sharpness, and image dry time while reducing HST and color-to-color bleed, achieving high brightness and waterfastness characteristics.

Implementation Method 1

optical brightening agents

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Implementation Method 2

reducing HST (Hercules Sizing Test Value)

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentUS7682438B2Paper substrate having enhanced print density

Publication Date: 2010.03.23 COBANK ACB AS ADMINISTRATIVE AGENT

AI summary

The present invention relates to a sizing composition that, when applied to paper substrate, creates a substrate, preferably suitable for inkjet printing, having increased print density, print sharpness, low HST, and/or image dry time, the substrate preferably having high brightness and reduced color-to-color bleed as well. In addition, the present invention relates to a method of reducing the HST of a paper substrate by applying the sizing composition to at least one surface thereof. Further, the application relates to methods of making and using the sizing composition, as well as methods of making and using the paper containing the sizing composition.