COMMON PROBLEMS IN THE PRODUCTION OF WATERPROOFING LEATHER: THE CHOOSE OF WET BLUE LEATHER AND THE WATERPROOFING PRODUCTS

Background description:

The structure of leather is composed of collagen fiber, tanning agent and other water-soluble chemical products, which has strong hydrophilicity. Therefore, making waterproof leather on this basis with both the use value and fashion is very difficult. It not only requires higher requirements for waterproofing products and production process, but also have strict requirements for waterproof supporting products, production environment and finishing.

In order to make waterproofing leather with outstanding performance and stable quality, it is inseparable from four elements: one is the quality control of wet blue leather, the second is the optimization of waterproofing product, the third is the selection of waterproof leather supporting products, and the fourth is the control of production process. This chapter focuses on the attention of blue wet leather and water repellent optimization.

The selection of wet blue leather

Due to the differences in processing technology and chemical materials adopted by fur processing enterprises, the quality of wet blue leather is uneven, which has a great impact on the quality of subsequent production of waterproofing leather. Therefore, identifying whether wet blue leather is suitable for waterproof leather production becomes the first important matter in waterproofing leather production.

1. Try to choose fresh wet blue leather, and remove dust to clean. If the storage time of wet blue leather is longer (more than 6 months), it is necessary to increase the chromium retanning to enhance the activity of wet blue leather and promote the uniform distribution of electric charge in the blue leather.

2. The wet blue leather which used for shoe upper should be tight and uniform with very small side difference.

3. Gloves, clothing and other soft waterproof leather can use conventional wet blue leather.

4. Wet blue leather should not be too absorbent.

Determination method of water absorption of wet blue leather:

1. Conventional detection method:

The clear water drops on the surface of dry wet blue leather, if the water beads and stay for more than 2 seconds, it is suitable for the production of waterproof leather; If water droplets spread out and penetrate immediately on the surface, this kind of wet blue leather is not suitable for the production of waterproofing leather.

2. Laboratory test method:

2.According to DM/CZ 05-532 "Test for oil and water resistance of leather

 Adjust the sample (dry wet blue leather) in the standard air for 24 hours, at the height of 1cm from the leather surface to take water vertically drop on the leather surface and start timing, until the water drop is completely absorbed by the leather stop timing, to determine the water absorption strength of the surface of wet blue leather water absorption time. Finally evaluate whether it is suitable for the production of waterproof leather.

The selection of waterproofing agent (oil)

According to the comprehensive performance requirements of waterproof leather, the optimal order of waterproof products from low to high: filling blocking type a surface hydrophobic type a reaction combined type a multiple compound, ultimately should be determined by the actual needs of customers.

Filling blocking type belongs to closed waterproof products, and the other three types are open waterproof products. With the increasing demand for functional comfort composite, people put forward higher requirements for the hygiene of leather products, so the choice of reaction combination type and multi-compound waterproof products become the leading industry.

Tingjiang waterproof products are open waterproof products, waterproof performance is extremely excellent, one of leather factories had done the limit test, dynamic waterproof breakthrough 120,000 times. And all products have passed the environmental protection testing of REACH, ZDHC and VF CHEM-IQ approved testing institutions, fully in line with the current environmental protection requirements of the leather industry. Different styles should be required to show their different effects, we can choose as needed.

1. Outdoor waterproof supplies, military combat boots production products recommended:

Style requirements: Full and firm leather body, excellent dynamic waterproof performance, and has certain siphon resistance.

Product recommendation: general waterproof agent GWP, rigid waterproof agent AWP

Performance comparison under the same process environment 

2. Recommended Labour protection products and garment leather products:

Style requirements: soft and plump leather body, short and dense velvet, and full dyeing, with good dynamic waterproof performance, and a certain ability to resist pollution.

Product recommendation: soft waterproof agent SWP, waterproof agent TJ-A9981

Performance comparison under the same process environment

3.High stability waterproofing agent suitable for complex environment

Style requirements: Suitable for complex environment, due to its high stability, hard water resistance, easy emulsification, high absorption and other characteristics, can adapt to a variety of operating environments, can also be normal operation in the room temperature water, even if the processing conditions are simple, rough operation of enterprises, still can produce high-quality waterproof products.

Product recommendation: high stability waterproof agent HWP

Performance comparison under the same process environment 

Due to space constraints, this chapter only introduces the first two elements of waterproof leather production, and will share other content with you next time. Based on the author's limited cognition, inevitably there is something wrong, welcome to correct!