Paper Surface Treatment Timing and Atomization
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Solution Overview
Problem
Existing methods for surface treating paper or board with reduced amounts of surface agents often result in poor printing quality due to uneven coverage and penetration of the treatment agents into the paper, making it difficult to achieve high printability with minimal application.
Innovation Solution
Applying a surface treatment agent between 5-100 milliseconds prior to or after a calender or breaker stack nip, while the paper or board is in contact with a roll, using a spraying method that atomizes the agent at elevated temperatures to create a heat and moisture gradient, preventing penetration and ensuring even coverage with minimal amounts (below 0.5 g/m²) of agents like starch or CMC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of surface treatment agent is reduced, then cost and environmental impact are improved, but printing quality deteriorates due to uneven coverage and penetration
Solution Approach 1:
The surface treatment agent is applied to the paper surface immediately before or after the calender nip, while the paper is still in contact with the calender roll. This timing ensures the agent is deposited on the heated, compressed surface before the paper moves away, maximizing retention and coverage efficiency with minimal agent quantity
Solution Approach 2:
The invention changes the physical state parameters of the surface treatment agent by applying it as an atomized spray at elevated temperatures (at least 80°C, preferably 90-100°C). This creates a heat and moisture gradient in the paper that prevents penetration and ensures even surface distribution, achieving high printing quality with reduced agent amounts
2Quantity of substance
If surface treatment agent is applied in reduced amounts, then material usage is improved, but surface coverage uniformity deteriorates
Solution Approach 1:
The surface treatment agent is applied in an atomized state, breaking the liquid into fine droplets that distribute evenly across the paper surface. This segmentation of the treatment agent into numerous small particles ensures uniform coverage even at low application rates
Solution Approach 2:
By applying the treatment agent at elevated temperatures (at least 80°C) in an atomized spray, the invention creates optimal physical conditions for even distribution. The heat and moisture gradient formed in the paper prevents capillary absorption and ensures the agent remains on the surface, achieving uniform coverage with minimal material
3Strength
If surface treatment agent is applied before calendering, then surface strength is improved, but agent penetration into paper increases
Solution Approach 1:
The surface treatment agent is applied immediately before or after the calender nip while the paper is in contact with the calender roll. This timing allows the agent to be deposited on the compressed, heated surface and rapidly set in place before the paper moves away, preventing penetration into the bulk
Solution Approach 2:
The invention utilizes phase transition by applying the treatment agent as an atomized spray at elevated temperatures (at least 80°C). The rapid evaporation of moisture from the atomized droplets on the heated paper surface creates a heat and moisture gradient that prevents liquid penetration while ensuring even surface distribution
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 high printing quality with significantly reduced surface treatment agent usage, maintaining surface strength and preventing agent penetration, thus eliminating the need for additional drying and enhancing gloss, smoothness, and bulk of the paper or board.
Implementation Method 1
Spraying of the high temperature treatment agent onto the surface of the paper/board gives rise to a high temperature at the surface of the paper/board. Preferably, the atomized medium comprising the surface treatment agent has a temperature of at least 80°C, preferably between 80-110°C even more preferably between 90-100°C, most preferably a temperature of 95°C. In this way, a heat and moisture gradient is formed in the paper/board, whereby the temperature at the surface of the paper/board is higher than the temperature inside the paper/board.
Implementation Method 2
The high temperature of the paper or board makes water applied together with the surface treatment agent to evaporate quickly whereby the surface treatment agent is kept on the surface of the paper or board.
Data Source
Figure 1
AI summary
The inversion relates to a method for the surface treatment of paper or board, which, method comprises adding a surface treatment agent to the paper or board and creating said paper or board in at least one calender ¾r breaker stack nip formed by a first: and a second calender or breaker stack roil* The method is characterized in that the surface treatment agent is applied onto the surface: of at least one side of the paper or board immediately prior to or after the calender or breaker stack hip,, while the paper or hoard is in contact with one of the calender or breaker stack rolls.. The method of the invention mates it possible to surface treat a paper or board with a small amount of a surface treatment agent f hut yet achieve a high printing quality at the printing of the surface, treated paper or board.