Paper Surface Sizing Composition for Brightness and Opacity
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Solution Overview
Problem
Uncoated papers lack desirable properties such as brightness, opacity, and print quality, which are typically achieved in coated papers at a higher cost, making it desirable to provide these properties in uncoated papers at a lower cost.
Innovation Solution
A paper surface sizing composition comprising acicular calcium carbonate pigment, a paper starch binder, and a co-binder, applied to one or both sides of the paper web, with specific weight ratios and Brookfield viscosity, to enhance brightness, opacity, and print quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uncoated paper is used, then cost is reduced, but brightness, opacity, and print quality deteriorate
Solution Approach 1:
The patent applies surface sizing treatment to uncoated paper with specific composition parameters (starch binder 30-99 wt%, co-binder 1-70 wt%, pigment 0.5-4 parts by weight relative to starch) and physical parameters (Brookfield viscosity 20-500 cP, solids content ≥8%). This parameter optimization enables uncoated paper to achieve brightness ≥80% and improved opacity without incurring coated paper costs
Solution Approach 2:
The patent uses inexpensive materials including starch binders, co-binders, and pigments in a surface sizing composition that can be applied to uncoated paper. This approach achieves coated-paper-like properties using low-cost components rather than expensive coated paper structures
2Ease of manufacture
If uncoated paper is used, then cost is reduced, but opacity deteriorates (print show-through increases)
Solution Approach 1:
The patent optimizes the pigment content parameter in the surface sizing composition (0.5-4 parts by weight relative to starch binder) and applies it to uncoated paper. This parameter adjustment achieves improved opacity and reduced print show-through while maintaining the uncoated paper cost structure
3Ease of manufacture
If uncoated paper is used, then cost is reduced, but print quality deteriorates
Solution Approach 1:
The patent carefully controls multiple parameters including starch binder content (30-99 wt%), co-binder content (1-70 wt%), pigment ratio (0.5-4 parts by weight), Brookfield viscosity (20-500 cP), and solids content (≥8%). This multi-parameter optimization enables uncoated paper to achieve print quality comparable to coated paper at lower cost
Solution Approach 2:
The patent creates a composite surface sizing composition combining starch binder, co-binder, and pigment in specific ratios. This composite material system applied to uncoated paper produces surface properties equivalent to coated paper, achieving high print quality without coated paper costs
4Illumination intensity
If starch binder content is increased, then brightness and print quality improve, but viscosity increases (affecting application)
Solution Approach 1:
The patent optimizes the starch binder content parameter within 30-99 wt% of total binder weight and controls Brookfield viscosity within 20-500 cP. This parameter balance ensures sufficient brightness improvement while maintaining application-friendly viscosity characteristics
Solution Approach 2:
The patent introduces co-binder as an intermediary component (1-70 wt% of total binder weight) that works synergistically with starch binder. This co-binder mediates between the brightness-enhancing effect of starch and the viscosity increase, enabling effective application while achieving desired optical properties
Data Source
AI summary
Embodiments of the present invention provide a paper surface sizing composition, a paper web coated on one or more sides or surfaces with a paper surface sizing composition, and a method for treating one or more sides of the paper web with a paper surface sizing composition to impart benefits relating to one or more of the following properties: (1) brightness; (2) opacity; (3) paper smoothness; (4) print quality; (5) optionally ink dry time (e.g., for ink jet printing where the sizing composition has option); and (6) optionally minimizing or eliminating edge welding (e.g., for paper webs used in, for example, form printing).