High-Bulk HT-CTMP From Controlled Hardwood–Spruce Blends

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing chemithermomechanical pulp (CTMP) processes do not fully leverage the potential of hardwood and spruce wood combinations to achieve improved bulk and reduced shives content, and there is a need for enhanced properties in CTMP production.

Innovation Solution

A high temperature chemithermomechanical pulp (HT-CTMP) is produced using a mixture of hardwood and spruce wood with a specific dry weight ratio, impregnated with sulfite and heated to at least 150°C, followed by defibration, to enhance fiber separation and reduce shives content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional CTMP processes are used, then production is maintained at existing levels, but bulk is insufficient and shives content is high

Engineering Contradiction:

ImprovebulkVSAvoidshives content

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by using a specific wood mixture ratio (hardwood to softwood between 65:35 and 20:80) and controlling the steam temperature at least 150°C during heat treatment. These parameter adjustments optimize the chemical and mechanical treatment to achieve higher bulk while reducing shives content, directly resolving the contradiction between volume and manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by combining hardwood and softwood in specific proportions (65:35 to 20:80 ratio) to create a mixed wood chip composition. This composite approach leverages the complementary properties of different wood types to produce CTMP with improved bulk and reduced shives, addressing both volume and precision requirements simultaneously.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If higher temperatures are used during heat treatment, then energy input during pressurized defibration decreases, but process complexity increases

Engineering Contradiction:

Improveenergy inputVSAvoidprocess complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by establishing a minimum steam temperature of 150°C during heat treatment, which reduces the energy input required in subsequent pressurized defibration. This parameter optimization directly addresses the energy consumption issue while the standardized temperature requirement keeps the process control manageable.

Inventive Principle:

Principle #35Parameter changes

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 HT-CTMP process results in a pulp with higher bulk and lower shives content, demonstrating improved freeness and tensile strength, as evidenced by pilot trials and full-scale system illustrations.

Implementation Method 1

followed by a heat treatment to soften the wood

Methodology Applied

Scientific EffectThermal heating: Heating

Implementation Method 2

Using steam of relatively high temperature in the heat treatment typically leads to a decrease in the energy input needed during the pressurized defibration step

Methodology Applied

Scientific EffectSteam condensation and heat transfer: Phase Change

Data Source

PatentEP4590892B1High-bulk ctmp

Publication Date: 2025.10.15 BILLERUD AB

Figure 1
Figure 2~3
Figure 4

AI summary

The present disclosure provides a high temperature chemithermomechanical pulp (HT-CTMP) formed from a mixture of hardwood and spruce wood, wherein the dry weight ratio of hardwood to spruce wood in said mixture is between 65:35 and 20:80. A method of producing HT-CTMP is also provided.