A process for tanning leathers including a pre-tanning step and a tanning step is provided. In the pre-tanning step leathers are treated with a cationic active agent including a quatemized ester of a fatty acid and triethanolamine, or mixtures thereof and, subsequently, with an anionic active agent including tannins vegetable extracts and a natural or synthetic dispersant selected from the group consisting of lignosulfonates, distillation stillages, sulfonated disulfonic polymers, sulfonated naphthalene polymers or mixtures thereof, to obtain leathers with a shrinkage temperature of at least 65° C. The pre-tanning and tanning steps do not include treatment with aldehydes or aldehyde donor compounds and/or with metal salts.

The present invention provides a method of manufacturing leather, which not only significantly suppresses the occurrence of adhesive wrinkling and boarding/alighting wrinkling when used for an automobile seat, for example, but also exhibits appropriate flexibility.

The present invention is a method of manufacturing leather including a pretreatment step, a tanning step, a retanning step, and a drying and finishing step in this order, the retanning process including, in the following order, subjecting a shaving leather obtained from the tanning process to a stage of performing treatment using a predetermined retanning agent and a predetermined resin, a stage of performing treatment using a predetermined retanning agent, a predetermined resin, and a predetermined fatliquoring agent, and a stage of performing treatment using a predetermined resin and a predetermined fatliquoring agent, and the drying in the drying and finishing process including, in the following order, subjecting a leather obtained from the retanning process to a stage of drying under reduced pressure under predetermined conditions and a step of drying at atmospheric pressure under predetermined conditions.

The present invention provides a method of manufacturing leather, which not only significantly suppresses the occurrence of adhesive wrinkling and boarding/alighting wrinkling when used for an automobile seat, for example, but also exhibits appropriate flexibility.

The present invention is a method of manufacturing leather including a pretreatment step, a tanning step, a retanning step, and a drying and finishing step in this order, the retanning process including, in the following order, subjecting a shaving leather obtained from the tanning process to a stage of performing treatment using a predetermined retanning agent and a predetermined resin, a stage of performing treatment using a predetermined retanning agent, a predetermined resin, and a predetermined fatliquoring agent, and a stage of performing treatment using a predetermined resin and a predetermined fatliquoring agent, and the drying in the drying and finishing process including, in the following order, subjecting a leather obtained from the retanning process to a stage of drying under reduced pressure under predetermined conditions and a step of drying at atmospheric pressure under predetermined conditions.

A composition including an acetal of an aldehydic tanning agent for tanning hides and/or pelts, as well as a method for tanning hides and/or pelts in order to produce leather, wherein an acetal of an aldehydic tanning agent is used. By reducing the pH, the aldehydic tanning agent can be released, whereby a tanning step is initiated. The composition according to the invention and the method according to the invention are characterized by lower toxicity compared to conventional compositions and tanning methods based on aldehydic tanning agents. Furthermore, improved penetration of the tanning agents into deeper layers of the hide and/or the pelt is possible, so that particularly homogeneous tanning is achieved.

A composition including an acetal of an aldehydic tanning agent for tanning hides and/or pelts, as well as a method for tanning hides and/or pelts in order to produce leather, wherein an acetal of an aldehydic tanning agent is used. By reducing the pH, the aldehydic tanning agent can be released, whereby a tanning step is initiated. The composition according to the invention and the method according to the invention are characterized by lower toxicity compared to conventional compositions and tanning methods based on aldehydic tanning agents. Furthermore, improved penetration of the tanning agents into deeper layers of the hide and/or the pelt is possible, so that particularly homogeneous tanning is achieved.

Modified polylactones, aqueous compositions including them, as well as their use and methods including their use as fatliquoring agents (fatliquors) in the treatment of leathers, including other embodiments.

A method of synthesizing a resin including mixing a first solution including a melamine compound with a second solution including glutaraldehyde to form a third solution, heating the third solution to 35 C. to 90 C. in at a pH above 7 for 5 to 70 minutes, and cooling the third solution to room temperature.

A method of synthesizing a resin including mixing a first solution including a melamine compound with a second solution including glutaraldehyde to form a third solution, heating the third solution to 35 C. to 90 C. in at a pH above 7 for 5 to 70 minutes, and cooling the third solution to room temperature.

The present invention is directed to a process for retanning leather comprising the steps of: a) providing tanned or pre-tanned leather b) treating the tanned leather of step a) with a composition comprising hollow microspheres, preferably as an aqueous composition, the hollow microspheres have a true density of from 0.01 to 0.10 g/cm.sup.3 (25? C.) and/or a bulk density of the dry powder of 0.005 to 0.06 g/cm.sup.3 (25? C.), c) drying, whereby the temperature of the leather during drying does not exceed 75? C. as well as to leather obtained by said process.

The present invention is directed to a process for retanning leather comprising the steps of: a) providing tanned or pre-tanned leather b) treating the tanned leather of step a) with a composition comprising hollow microspheres, preferably as an aqueous composition, the hollow microspheres have a true density of from 0.01 to 0.10 g/cm.sup.3 (25? C.) and/or a bulk density of the dry powder of 0.005 to 0.06 g/cm.sup.3 (25? C.), c) drying, whereby the temperature of the leather during drying does not exceed 75? C. as well as to leather obtained by said process.