Suede Production And Process Difficulties

coriginally refers to the leather made of animal suede, which looks very similar to deer. However, we can see from the picture below that the suede skin is different from the suede we usually see, and it does not have short and dense hair.

This is because the animal's epidermis and hair must be stripped off during the leather processing process, and only the grain layer and the flesh layer are used. Suede often lives in the jungle and is injured by branches, rocks, and even other animals, resulting in more injuries to the grain layer of the skin. If it is directly processed and used, the quality is poor. Usually, the grain layer is sanded to cover the scratches to obtain a better appearance. Because of this, a unique suede style is obtained.

Over time, people also like to call this suede-processed leather "suede".

Since suede is a national second-level protected animal, natural suede is also replaced by deerskin, goat skin, sheep skin, pig skin, and cow skin, and the suede style is obtained by sanding the grain layer.

However, with the development of the times and the progress of the industry, the feel and appearance of suede-like fabrics in the textile printing and dyeing industry are quite similar to natural suede, and its surface texture structure is also similar to natural suede. After special finishing, it is fine, smooth, soft and plump, more durable and easier to maintain than natural suede.

Suede production and processing technology

The production methods of artificial suede can be roughly divided into three types: weaving method, knitting method, and non-woven fabric method.

Suede-like weaving process:

Weaving: Grey cloth - desizing, refining, relaxing, alkali reduction (fiber opening) → pre-shaping, brushing, dyeing → reduction, cleaning, finishing → shaping → finished product

Knitting: Warp knitting, grey cloth, brushing, shearing - pre-shaping, refining, relaxing, alkali reduction (fiber opening) - dyeing, reduction, cleaning, pre-shaping, brushing, finishing → finishing → finished product

Weft knitting, grey cloth - refining, relaxing, alkali reduction (fiber opening) - dyeing → reduction, cleaning, slitting → pre-shaping, brushing, brushing, finishing → finishing → finished product

Suede raw material island fiber: Island fiber is also called matrix fibril. It is formed by a polymer in an extremely fine form (fibril) embedded in another polymer (matrix). Because the dispersed phase fibril is in the state of islands in the fiber cross section, and the continuous phase matrix is in the state of the sea, it is also figuratively called island fiber.

Dyeing process: Since the sea island microfiber artificial leather is composed of micro-polyamide fiber and polyurethane, and the micro-polyamide fiber has a fast dyeing speed, poor leveling and dyeing depth, large dye consumption, and low dyeing fastness, the polyurethane fiber has different affinity for dyes, which affects the uniformity of dyeing, so its dyeing is very difficult.

For this reason, a large number of tests on dyes, auxiliaries and dyeing processes are required, and suitable dyes and auxiliaries are selected to determine the appropriate dyeing process to achieve the goals of uniform dyeing, deep dyeing, and dyeing through, as well as maintaining high color fastness.

The general dyeing process is: 1%~3% leveling agent, 1~3g/L penetrant, acid release agent to adjust the pH value to 4~8, add the required dye, and then raise the temperature to 35℃, 1C/min to 65℃, 0.4℃/min to 105℃, keep warm for 90~120min, then cool down, wash with water or perform necessary post-treatment.

According to different product uses and different user requirements, the post-processing process can be used to carry out three kinds of post-processing on the products, such as antibacterial, flame retardant, UV protection, etc. Special finishing is also carried out according to different requirements, such as printing, veneer, embossing, hot stamping, magnetization, carbonization, atomization, breathability, fragrance treatment, etc.

PU post-finishing: All suede-like materials must be impregnated with PU resin, which will affect the feel of suede-like materials. The PU resin used for suede-like materials has the following characteristics: it has a certain elasticity; it has a certain plasticity; its characteristics do not change with temperature; it has a low glass transition temperature and a high softening point; it is soluble during processing; it has porosity.

Key points of production process

In the analysis of the production process, there are three crucial links for the success of suede-like production.

1. The quality of raw materials and the selection of fiber-dissolving formula: to ensure the stability of the quality of the finished cloth, it is required to ensure that the raw materials are first-class and of the same batch number. The fiber dissolving formula uses a special high-temperature alkaline water (150℃, pH=13~14 water) that matches the raw materials.

2. Weaving process: The pre-weaving must be twisted or coated evenly. The vacuum degree and the process selection of temperature rise and fall are very important during shaping, otherwise the fabric will easily have color spots after dyeing.

3. Sanding dyeing and suede treatment: The sanding effect is not good, which will produce dark and light colors. The sanding of the fabric is completed by cutting with corundum. The sanding mesh is small and the corundum particles are large. The force on the fabric during the sanding process is large, and the fluff is long. At the same time, the strength of the fabric is also greatly reduced. On the contrary, if the sanding mesh is too large, sanding is more difficult and the cost is correspondingly increased.

The five-pass sanding roller adopts the "heavy first and light later" sanding process, that is, the first sanding roller uses a lower mesh sanding belt, the purpose is to pull out as many fibers in the yarn as possible and cut them into single fibers; the last four sanding rollers use a relatively high mesh sanding belt, the purpose is to continue to pull out and cut the fibers in the yarn, and more importantly, to grind the pulled and cut single fibers into fluff, so that the ground fluff can better achieve the effect of "fine, short, dense and uniform".

The tension during dyeing is also very important. Excessive tension will cause hair loss, such as chicken claw-shaped defects.

Suede treatment is mainly for suede softening treatment, and the quality of the treatment directly affects the fabric feel and wearing performance.

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If you want to know more about dyeing solutions, please contact: info@tiankunchemical.com