Abstract: Provided is a natural leather having a novel coating layer which feels leathery. The coating film retains material properties such as strength and wearing resistance. When the user directly touches the natural leather, the coating layer present on the surface of the natural leather gives slick characteristics of natural leathers and smoothness. The natural leather has a coating film formed on a surface thereof, the coating film including: a color coat layer formed from a mixture of a hard component (10% modulus is more than 2.3 but no more than 3.0) and a soft component (10% modulus is more than 0.0 but no more than 1.0) of a two-component polyurethane resin; and a topcoat layer formed from a mixture of a medium component (resin having a 10% modulus of more than 1.0 but no more than 2.3) and a soft component (resin having a 10% modulus of more than 0.0 but no more than 1.0) of a two-component polyurethane resin.

Abstract: Provided are novel solubilized collagen fibers with which solubilized collagen can be obtained by instantaneous uniform dissolution in water at the time of use. The solubilized collagen fibers are formed from a solubilized collagen solid content of 66 to 87 wt %, buffer salt content of 2 to 6 wt %, water content of 10 to 22 wt %, and a residual hydrophilic organic solvent content of a trace amount of up to 6 wt % (totaling 100 wt %). The solubilized collagen fibers have an average fineness of 3 to 10 dtx, an isoionic point of 4.5 to 5.0, a water content of 10 to 22 wt %, and residual hydrophilic organic solvent content of a trace amount of up to 6.0 wt %. The solubilized collagen fibers are present uniformly in the direction of fiber length. The buffer salt is selected from sodium citrate, sodium lactate, and sodium phosphate.

Abstract: A leather obtained by a (1) pre-treatment before tanning, (2) tanning process where glutaraldehyde is used as a tanning agent, (3) process where a re-tanning agent is used which is constituted by synthetic tannin, resin and aluminum, of which the synthetic tannin is constituted by (a) condensation product of aromatic sulfonic acid with formaldehyde or mixture of aromatic sulfonic acid and condensation product of aromatic sulfonic acid with formaldehyde, (b) methylene cyclic polymer of aromatic sulfonic acid with hydroxy aromatic compound or mixture of aromatic sulfonic acid and methylene cyclic polymer of aromatic sulfonic acid with hydroxy aromatic compound and (c) glyoxal, while the resin is constituted by (a) acrylic acid, methacrylic acid, acrylic acid ester or methacrylic acid ester polymer(s) and mixture thereof, and copolymer(s) thereof or mixture thereof and (b) polycondensation product of melamine with formaldehyde, wherein the re-tanning agent having the aforementioned composition is used to perform

Abstract: Disclosed is solubilized collagen fiber ball: that is crimped and does not have fiber separation defects within which the amount of water content and the amount of hydrophilic organic solvent are evenly distributed; and that dissolve instantly and uniformly when used. The fiber ball has a composition that may comprise 66 to 87 wt % solubilized collagen, 2 to 6 wt % buffer salt, 10 to 22 wt % water content, and a trace amount to 6 wt % residual hydrophilic organic solvent, and is 3 to 25 mm in diameter, weighs 3 to 20 mg, has an average fiber size of 3 to 10 dtx, and a length of 1 to 20 cm. The fiber ball, which has a wavy shape and comprises uniform bundles of solubilized collagen fibers formed in a spherical shape, may have a bulk density of 4.0 to 8.0 mg/cm3, and a swab diameter of 3 to 25 mm.

Abstract: Provided are novel solubilized collagen fibers with which solubilized collagen can be obtained by instantaneous uniform dissolution in water at the time of use. The solubilized collagen fibers are formed from a solubilized collagen solid content of 66 to 87 wt %, buffer salt content of 2 to 6 wt %, water content of 10 to 22 wt %, and a residual hydrophilic organic solvent content of a trace amount of up to 6 wt % (totaling 100 wt %). The solubilized collagen fibers have an average fineness of 3 to 10 dtx, an isoionic point of 4.5 to 5.0, a water content of 10 to 22 wt %, and residual hydrophilic organic solvent content of a trace amount of up to 6.0 wt %. The solubilized collagen fibers are present uniformly in the direction of fiber length. The buffer salt is selected from sodium citrate, sodium lactate, and sodium phosphate.

Abstract: Provided are a car-seat split crust leather and leather. A hide already subjected to pretreatment and subjected to tanning treatment is split into leather including a grain surface and into split leather with a thickness of 4 mm to 2.3 mm, the taken-out split leather is arranged so that a flesh side of the split leather can be located on an upper side and that a grain side of the split leather can be located on a lower side, split leather with a thickness of 2.6 mm to 1.8 mm is made, next, the flesh side of the split leather is shaved to thereby set the thickness of the split leather to 2.0 mm to 1.1 mm, and a car-seat split crust leather with a thickness of 1.6 mm to 1.0 mm is manufactured, which is then subjected to tanning and re-tanning treatment, and has a coating film formed thereon.

Abstract: A natural leather is treated with a tanning agent, a re-tanning agent, a dye and a greasing agent, wherein a treatment agent for inhibiting the generation of formaldehyde and acetaldehyde from the natural leather is added to the greasing step so that the natural leather is impregnated with the treatment agent. The treatment agent includes a hydrazide compound optionally together with sodium hydrogen sulfite.

Abstract: Provided is a natural leather having a novel coating layer which feels leathery. The coating film retains material properties such as strength and wearing resistance. When the user directly touches the natural leather, the coating layer present on the surface of the natural leather gives slick characteristics of natural leathers and smoothness. The natural leather has a coating film formed on a surface thereof, the coating film including: a color coat layer formed from a mixture of a hard component (10% modulus is more than 2.3 but no more than 3.0) and a soft component (10% modulus is more than 0.0 but no more than 1.0) of a two-component polyurethane resin; and a topcoat layer formed from a mixture of a medium component (resin having a 10% modulus of more than 1.0 but no more than 2.3) and a soft component (resin having a 10% modulus of more than 0.0 but no more than 1.0) of a two-component polyurethane resin.

Abstract: This object relates to a leather which is obtained by forming a coating film through the greasing step following re-tanning and dyeing and the drying step. The purpose of this object is to provide a leather, wherein the generation of free formaldehyde and acetaldehyde is inhibited, an automobile interior part using this leather and a back sizing agent for natural leather to be used for producing the above-described leather.

Abstract: A leather is obtained by a process where a re-tanning agent is used which is constituted by synthetic tannin, resin and aluminum. The synthetic tannin is constituted by (a) condensation product of aromatic sulfonic acid with formaldehyde, (b) methylene cyclic polymer of aromatic sulfonic acid with hydroxy aromatic compound, and (c) glyoxal. The resin is constituted by (a) acrylic acid, methacrylic acid, acrylic acid ester or methacrylic acid ester polymer(s), and copolymer(s) thereof, and (b) polycondensation product of melamine with formaldehyde.

Abstract: This invention provides a natural leather having a coating film as a topcoat layer that can suppress and prevent the occurrence of an uncomfortable squeak noise and, at the same time, has softer feeling, soft and smooth feeling, and slick feeling, a composition for the formation of a coating film on a natural leather, and a process for producing a natural leather.

Abstract: This object relates to a natural leather which is obtained by forming a coating film through the greasing step following re-tanning and dyeing and the drying step. The purpose of this object is to provide a natural leather, wherein the generation of free formaldehyde and acetaldehyde is inhibited, and a treating agent to be added in the greasing step for natural leather. A natural leather wherein formaldehyde and acetaldehyde generated by a tanning agent, a re-tanning agent, a dye and a greasing agent having been incorporated into a leather are confined in the leather with a treating agent to be added in the greasing step for natural leather which contains a hydrazide compound optionally together with sodium hydrogen sulfite to thereby inhibit or prevent the generation of formaldehyde and acetaldehyde, and an automobile interior part coated with this natural leather.

Abstract: The present invention relates to a process for preparing regenerated collagen fiber which comprises treating regenerated collagen fiber with a monofunctional epoxy compound and a metal aluminum salt, in which treatment with the monofunctional epoxy compound initiated by adding sodium hydroxide to become 0.001 to 0.8 N based on the treatment solution and inorganic salt in an amount so that water absorption of the obtained regenerated collagen fiber becomes at most 100%, depending on amount of sodium hydroxide added. Also, the present invention relates to a process for setting regenerated collagen fiber obtained by the above process which comprises thermally setting the fiber by means of wet heat treatment at 50° to 160° C. and drying treatment at 20° to 220° C.

Abstract: The present invention provides regenerated collagen fibers which have light color and excellent touch in wet conditions and which can be formed into desirable shape with the shape being maintained properly. The present invention also provides regenerated collagen fibers whose foul odor generated in thermal treatment can be inhibited. The present invention relates to regenerated collagen fibers obtained by treating collagen with a monofunctional epoxy compound and an aluminum salt. The present invention also relates to a process for preparing regenerated collagen fibers which comprises treating collagen with a monofunctional epoxy compound, and then treating the same in such a way that 2 to 40% by weight of an aluminum salt converted to an aluminum oxide (Al2O3) basis is contained to said collagen.