Cutting and double-face leather integrated dyeing process for tan sheep skin
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Solution Overview
Problem
Existing processes for dyeing Tan sheep fur often result in pollution, cross-coloring, color fading, and low color fastness, making it difficult to achieve superior quality double-face leather with uniform dyeing.
Innovation Solution
A cutting and double-face leather integrated dyeing process for Tan sheep skin involving specific steps such as cutting, washing, retanning, primary and secondary dyeing, fatliquoring, color fixing, bleaching, and drying, with controlled temperature, pH, and auxiliary agents to prevent dye defects and ensure uniformity and high color fastness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dyeing processes (bath dyeing, brush dyeing, spray dyeing) are used on Tan sheep skin, then the dyeing process can be completed, but the leather board and fleeces pollute each other causing cross-coloring, color fading, and low color fastness
Solution Approach 1:
The patent divides the dyeing process into two separate stages: primary dyeing for the leather board and secondary dyeing for the fleeces. This segmentation prevents cross-coloring by treating each component independently with dedicated dye baths, eliminating the pollution problem between leather board and fleeces while ensuring high color fastness for both parts.
2Ease of manufacture
If Tan sheep skin of lower quality (third grade) is processed, then production costs are reduced and more material can be utilized, but the dyeing uniformity and quality are insufficient
Solution Approach 1:
The patent applies different dyeing conditions to different parts of the Tan sheep skin. The primary dyeing process targets the leather board with specific temperature, pH, and dye concentration, while the secondary dyeing process targets the fleeces with different parameters. This local quality approach ensures uniform dyeing even on lower quality third-grade skin by optimizing conditions for each specific component.
Solution Approach 2:
The patent controls and changes multiple process parameters including temperature (60-70°C for primary, 25-30°C for secondary), pH values (2.5-3.5 for primary, 2.0-3.0 for secondary), and dye concentrations to achieve uniform dyeing on third-grade Tan sheep skin. These parameter optimizations transform lower quality material into high-quality dyed products with excellent uniformity.
3Reliability
If the leather board is dyed first, then the fleeces can be dyed, but the process time and complexity increase
Solution Approach 1:
The patent performs preliminary action by completing the primary dyeing of the leather board first, allowing it to dry and set the color before proceeding to the secondary dyeing of the fleeces. This preliminary action prevents dyeing defects and ensures color stability, while the sequential arrangement optimizes the total process time by avoiding rework and corrections.
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 process achieves high color fastness, uniform dyeing, and maintains the softness and flexibility of the leather, preventing issues like stiff boards and fur shedding, thereby enhancing product value and reducing production costs.
Implementation Method 1
1.5-5 g/L of acid dye; 2-4 g/L of leather board dye
Implementation Method 2
putting 0.5-1.0 ml/L of formic acid into the paddle every 30 minutes for two to three times; putting 1.5-2.0 ml/L of formic acid into the paddle
Implementation Method 3
said fatliquoring agent including 3 ml/L of fatliquoring agent GH and 4 ml/L of fatliquoring agent FLP
Implementation Method 4
the temperature for the retanning treatment in S3 is 35-40° C., lasting for 24 hours, and a retanning agent used in the retanning treatment includes 6-10 g/L of chromium powder
Data Source
AI summary
A cutting and double-face leather integrated dyeing process for Tan sheep skin, which comprises the following steps: cutting→washing with water→retanning→primary dyeing→primary color fixing→secondary dyeing→fatliquoring→secondary color fixing→bleaching→drying→a finished product. Tan sheep skin leather boards and fleeces dyed by the process of the invention have no cross color and color fading with each other, a high color fastness, and uniform dyeing; the prepared Tan sheep skin products such as clothing, etc., not only have the characteristics of a high added value and good practicability, but also can more largely increase product benefits and lower the production cost.