阅读说明：本技术 可降低游离甲醛含量的超支化聚合物皮革复鞣剂 (Hyperbranched polymer leather retanning agent capable of reducing content of free formaldehyde ) 是由 田赛琦 丁昇 朱一凡 陈银燕 于 2020-11-30 设计创作，主要内容包括：本发明公开了一种可降低游离甲醛含量的超支化聚合物皮革复鞣剂,以季戊四醇为核,用六亚甲基二异氰酸酯、季戊四醇、六亚甲基二异氰酸酯相继扩链,最后用三缩四乙二胺进行封端,制备含有多氨基的超支化聚合物。本发明的复鞣剂具有良好复鞣性能,且鞣剂分子中的氨基、亚氨基,可以有效降低皮革内的游离甲醛含量,从而实现“复鞣除醛一体化”,简化工序,节约成本和能耗。(The invention discloses a hyperbranched polymer leather retanning agent capable of reducing the content of free formaldehyde, which takes pentaerythritol as a core, uses hexamethylene diisocyanate, pentaerythritol and hexamethylene diisocyanate to carry out chain extension in sequence, and finally uses tetraethylene triamine to carry out end capping to prepare hyperbranched polymer containing polyamino. The retanning agent disclosed by the invention has good retanning performance, and amino and imino in molecules of the retanning agent can effectively reduce the content of free formaldehyde in leather, so that the integration of retanning and aldehyde removal is realized, the process is simplified, and the cost and the energy consumption are saved.)

1. A hyperbranched polymer leather retanning agent capable of reducing the content of free formaldehyde is characterized in that: comprises the following steps of (a) carrying out,

mixing 34 parts of pentaerythritol and 672 parts of hexamethylene diisocyanate, adding 0.6-1.2 parts of catalyst, keeping the temperature at 70-80 ℃, reacting for 40-50 min under the nitrogen atmosphere, adding 136 parts of pentaerythritol, keeping the temperature at 70-80 ℃, reacting for 40-50 min, adding 672 parts of hexamethylene diisocyanate, keeping the temperature at 70-80 ℃, reacting for 40-50 min, cooling to 40-50 ℃, adding 756 parts of tetraethylenetriamine, keeping the temperature at 40-50 ℃ and reacting for 20-30 min to obtain the hyperbranched polymer leather retanning agent capable of reducing the content of free formaldehyde.

2. Hyperbranched polymer leather retanning agent capable of reducing the content of free formaldehyde according to claim 1, characterized in that: the catalyst is any one of bismuth decanoate, bismuth laurate, bismuth isooctanoate, bismuth naphthenate, bis-dimethylaminoethyl ether or dimethylcyclohexylamine.

Technical Field

The invention relates to the technical field of chemical macromolecules, in particular to a hyperbranched polymer leather retanning agent capable of reducing the content of free formaldehyde.

Background

China is a big leather-making country, and the annual output value is about 1.35 trillion. The natural leather takes animal hide as a raw material, and is subjected to a series of complex physical and chemical processes, so that the natural polymer has better physical and mechanical properties, excellent sanitary performance and elegant appearance and texture, and is widely applied to various daily necessities and industrial products for a long time. Retanning is to perform one more tanning on tanned leather blanks, which has a large proportion in the whole leather making process, and through retanning, the chemical stability of leather can be improved, the body bones and grain surfaces of the leather can be improved, the leather yield can be increased, and the leather can be endowed with certain special properties. The quality of the retanning material is an important factor in determining the retanning effect.

In recent years, hyperbranched polymers have attracted extensive interest of researchers in the tanning industry due to their novel structures and unique properties. Compared with the traditional linear polymer, the hyperbranched polymer is highly irregular and has a three-dimensional structure, and the unique body structure of the hyperbranched polymer plays a role in filling among leather fibers, so that the finished leather is plump and soft. The terminal group of the hyperbranched polymer has a large number of active groups, such as hydroxyl, carboxyl or amino, and the like, which can form hydrogen bonds with hydroxyl, amino, carboxyl and the like on leather collagen fibers or coordinate bonds with chromium in wet blue leather, so that the collagen fibers are subjected to a crosslinking action, the physical and mechanical properties of the leather are improved, and the shrinkage temperature (Ts) is increased, thereby endowing the leather with a retanning effect. With the progress and development of the times, the demand of people for high-performance and high-quality leather products is continuously increased, and the leather products with single performance cannot meet the demand of consumers. At present, in order to reduce the problem of hexavalent chromium pollution caused by a chromium tanning method, an aldehyde tanning agent is selected to replace or partially replace the chromium tanning agent in a tanning process, however, the high content of free formaldehyde in aldehyde tanned leather is an important factor for limiting the aldehyde tanning agent, the content of free formaldehyde in leather is an important index for checking whether a finished leather product is qualified, and the development of a retanning agent capable of reducing free formaldehyde becomes a key for promoting the use of the aldehyde tanning agent.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the hyperbranched polymer leather retanning agent capable of reducing the content of free formaldehyde, and the retanning agent meets the requirement of a retanning procedure in the leather industry, realizes the reduction of the content of the free formaldehyde in the leather, can save the cost and energy consumption, and promotes the clean production of the leather industry.

In order to achieve the purpose, the invention provides a hyperbranched polymer leather retanning agent capable of reducing the content of free formaldehyde, which comprises the following steps of mixing 34 parts of pentaerythritol and 672 parts of hexamethylene diisocyanate, adding 0.6-1.2 parts of a catalyst, keeping the temperature at 70-80 ℃, reacting for 40-50 min under the nitrogen atmosphere, adding 136 parts of pentaerythritol, keeping the temperature at 70-80 ℃, reacting for 40-50 min, adding 672 parts of hexamethylene diisocyanate, keeping the temperature at 70-80 ℃, reacting for 40-50 min, cooling to 40-50 ℃, adding 756 parts of tetraethylene triamine, keeping the temperature at 40-50 ℃, and reacting for 20-30 min to obtain the hyperbranched polymer leather retanning agent capable of reducing the content of free formaldehyde.

As a further configuration of the present invention, the catalyst in the first step and the second step is any one of bismuth decanoate, bismuth laurate, bismuth isooctanoate, bismuth naphthenate, bis-dimethylamino ethyl ether or dimethyl cyclohexylamine.

The beneficial effect who so sets up is: firstly, the dosage ratio of each component in each step is calculated by weight, the antibacterial hyperbranched polymer retanning agent has low toxicity and strong biodegradability, can reduce potential pollution caused by the use of a metal salt retanning agent, does not use organic estimation in the preparation process, and meets the requirement of leather greening; meanwhile, each molecule of the antibacterial hyperbranched polymer retanning agent has 12 hydroxyl groups and 12 carboxyl groups, so that hydrogen bonds can be easily formed with active groups on collagen fibers of leather, coordination bonds can be easily formed with chromium in wet blue leather, and the shrinkage temperature of finished leather can be increased;

the existing method for removing formaldehyde in leather and fur mainly uses a formaldehyde trapping agent, and the formaldehyde trapping agent can be combined with formaldehyde in a chemical bond form without influencing other components to generate another stable compound, so that the formaldehyde content in the leather and fur is reduced. The ammonia and its derivatives in the formaldehyde trapping agent can generate nucleophilic addition with formaldehyde to generate non-toxic, harmless and stable compounds. The method for eliminating formaldehyde by using the derivative of ammonia has the advantages of high degradation speed, small reagent dosage, good degradation effect, safety, harmlessness, simple and convenient operation and the like. Furthermore, the retanning agent can realize the integration of retanning and aldehyde removal, simplify the process and save the cost and the energy consumption.

Drawings

FIG. 1 is a schematic diagram of the preparation of a hyperbranched polymer leather retanning agent capable of reducing the content of free formaldehyde according to an embodiment of the present invention.

Detailed Description

The first embodiment of the hyperbranched polymer leather retanning agent of the invention which can reduce the content of free formaldehyde is shown as follows: the method comprises the following steps of mixing 34 parts of pentaerythritol and 672 parts of hexamethylene diisocyanate, adding 0.6 part of bismuth decanoate, keeping the temperature at 80 ℃, reacting for 50min under the nitrogen atmosphere, adding 136 parts of pentaerythritol, keeping the temperature at 80 ℃, reacting for 50min, adding 672 parts of hexamethylene diisocyanate, keeping the temperature at 80 ℃, reacting for 50min, cooling to 50 ℃, adding 756 parts of tetraethylene triamine, keeping the temperature at 50 ℃, and reacting for 30min to obtain the hyperbranched polymer leather retanning agent capable of reducing the content of free formaldehyde.

A second embodiment of the hyperbranched polymer leather retanning agent of the invention, which can reduce the free formaldehyde content, is shown below: the method comprises the following steps of mixing 34 parts of pentaerythritol and 672 parts of hexamethylene diisocyanate, adding 1.2 parts of bismuth laurate, keeping the temperature at 70 ℃, reacting for 40min under the nitrogen atmosphere, adding 136 parts of pentaerythritol, keeping the temperature at 70 ℃, reacting for 40min, adding 672 parts of hexamethylene diisocyanate, keeping the temperature at 70 ℃, reacting for 40min, cooling to 40 ℃, adding 756 parts of tetraethylene triamine, keeping the temperature at 40 ℃, and reacting for 20min to obtain the hyperbranched polymer leather retanning agent capable of reducing the content of free formaldehyde.

A third embodiment of the hyperbranched polymer leather retanning agent of the invention that can reduce the free formaldehyde content is shown below: comprises the following steps of (a) carrying out,

mixing 34 parts of pentaerythritol and 672 parts of hexamethylene diisocyanate, adding 0.9 part of bis-dimethylamino ethyl ether, keeping the temperature at 75 ℃, reacting for 45min under the nitrogen atmosphere, adding 136 parts of pentaerythritol, keeping the temperature at 75 ℃, reacting for 45min, adding 672 parts of hexamethylene diisocyanate, keeping the temperature at 75 ℃, reacting for 45min, cooling to 45 ℃, adding 756 parts of tetraethylene diamine, keeping the temperature at 45 ℃, and reacting for 25min to obtain the hyperbranched polymer leather retanning agent capable of reducing the content of free formaldehyde.

The above examples are only a few of the preferred embodiments of the present invention, and general changes and substitutions by those skilled in the art within the technical scope of the present invention are included in the protection scope of the present invention.