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Coated natural leather having low deformation

A natural leather and leather technology, applied in the field of natural leather, can solve the problems of permanent deformation, coating can not provide enough recovery performance, etc.

Inactive Publication Date: 2003-07-02
EI DU PONT DE NEMOURS & CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The abrasion resistance and water resistance of the leather are improved, but the coating does not provide sufficient recovery properties to avoid permanent deformation of the coated leather after being highly stretched

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0027] The method for preparing coated leather of the present invention comprises the steps of: providing natural leather with an elongation ≥ 15% and capable of absorbing a polyurethane solution; making an elastic polyurethane solution with a viscosity of about 1,000-300,000 cPs, preferably 5,000-200,000 cPs applied to the flesh side of the leather; the coating is then dried, preferably at a temperature not higher than about 75°C, by evaporating solvents, etc., wherein the coating on the coated leather is approximately 5-70wt% of the weight.

[0028] The polyurethane solution can be applied at the "wet chrome tanned" stage of tanning, which is after chrome tanning but before retanning, coloring or oiling, drying, etc. However, during subsequent processing, some polyurethane may be lost as the deformation rate gradually increases. The application of polyurethane in the early stages of the tanning operation is preferably done after the leather has been stripped to the desired ...

Embodiment 1

[0039] Under vigorous mechanical stirring, 125 g of crushed elastic fiber was dissolved in 1 liter of dimethylformamide (DMF), which contained 1.25 g of diammonium hydrogen phosphate to aid dissolution. The resulting solution was protected from air by covering the vessel with a parafilm. After stirring for several hours, the Brookfield viscosity of the solution was measured to be about 7500 cPs at 21°C and 60% relative humidity. Calfskin samples with a thickness of 0.9 mm were chrome-tanned and dyed black. It weighs 81.0 g and has an elongation of 25-30%. The leather is coated on its flesh side with a polyurethane urea (PU) solution. The coated leather is then left to dry horizontally at room temperature. After 24 hours, the dried leather weighed 88.5 g, which represented 9.2% by weight of the polymer coating, based on the weight of the uncoated leather. The coated leather was tested as described above. The results are given in Table I.

[0040] Elongation at ...

Embodiment 2

[0043] The flesh side of tanned wool leather with a thickness of about 1 mm and an elongation of about 40% is coated with a DMF solution in which 12.5 wt % of polyurethane urea is dissolved. The solution viscosity was 120,000 cPs. The coated leather was dried at room temperature to yield a coating weight of 6.9%, based on the weight of the uncoated leather. After drying, the samples were somewhat stiff, so were bent and extended by hand for about half a minute. Their properties were then measured and given in Table II.

[0044] Elongation at 0N / cm (%)

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Abstract

Coated natural leather, prepared from natural leather having polyurethane coated on its flesh side and having an improved (decreased) measure of deformation, is provided.

Description

technical field [0001] The present invention relates to coated natural leather, and more particularly to leather coated with polyurethane or polyurethane urea on the flesh side. Background technique [0002] Natural leather is often coated on its grain for aesthetics, water resistance or durability. Although some applications of applying polymers to the flesh side of leather have been disclosed, the results have been less than satisfactory with regard to their extensibility and retraction. [0003] French patent 2,129,056 discloses a method of reinforcing leather by coating its flesh side with a hard cross-linked polyurethane elastomer, wherein the polymer is formed in situ on the leather. Shoes made of coated leather are also disclosed, but because the polymer is hard, neither the leather nor the shoe has the extensibility and recovery required for comfortable wearing. [0004] German Patent 1,469,530 discloses a method of impregnating the non-spe...

Claims

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Application Information

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IPC IPC(8): B68F1/00C08G18/10C08G18/42C08G18/48C09D175/02C14C11/00
CPCC08G18/4854C08G18/4238C09D175/02C14C11/006C08G18/10Y10T428/31558Y10T428/249991C08G18/3228C08G18/2865C14C11/00
Inventor 叶雷·A·门多萨埃莱尼·卡拉伊阿尼
Owner EI DU PONT DE NEMOURS & CO
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