Leather-like sheet and process for producing the same

Patent metadata

Field	Value
Publication number	US-9334609-B2
Application number	US-67557308-A
Country	US
Kind code	B2
Filing date	Aug 28, 2008
Priority date	Aug 28, 2007
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

A leather-like sheet containing a microfine long-fiber nonwoven fabric containing an entangled web structure made of bundles of microfine long fibers and an elastic polymer impregnated in the microfine long-fiber nonwoven fabric. The leather-like sheet has a machine direction/transverse direction ratio of breaking strength of 1/1 to 1.3/1, an elongation at break in each of the machine direction and the transverse direction of 80% or more, and a machine direction/transverse direction ratio of elongation at break of 1/1 to 1/1.5. The leather-like sheet has a natural dense feeling, a soft hand, a small difference of mechanical properties in the machine direction and the transverse direction, a moderate resistance to elongation and a durable recovery.

First claim

What is claimed is:

1. A leather-like sheet which comprises a microfine long-fiber nonwoven fabric comprising an entangled web structure comprising bundles of microfine long fibers and an elastic polymer impregnated in the microfine long-fiber nonwoven fabric, wherein
(1) each of the bundles of microfine long fibers comprises 5 to 70 microfine long fibers having an average single fiber fineness of 0.5 dtex or less;
(2) the bundles of microfine long fibers have an average fineness of 3 dtex or less;
(3) the entangled web structure comprises superposed webs, wherein the superposed webs comprise a long-fiber web obtained from composite fibers by a spun-bonding method, wherein the composite fibers are capable of converting into the bundles of microfine long fibers, and wherein each of the superposed webs comprises the bundles of microfine long fibers;
(4) a web orientation angle in the leather-like sheet is 73° or more, wherein the web orientation angle in the leather-like sheet is the web orientation angle at least after an entangled treatment and a microfine-fiberization;
(5) a ratio of the microfine long fibers and the elastic polymer is 70/30 to 40/60 by mass;
(6) the elastic polymer is substantially continuous;
(7) the leather-like sheet comprises an oil agent in an amount of 0.1 to 10 mass % on the basis of the leather-like sheet; and
(8) a machine direction/transverse direction ratio of breaking strength is 1/1 to 1.3/1, an elongation at break in each of the machine direction and the transverse direction is 80% or more, and a machine direction/transverse direction ratio of elongation at break is 1/1 to 1/1.5,
and wherein the leather-like sheet satisfies the following properties (i) to (viii):
A 1≦40%  (i)

B 1≦15%  (ii)

10%≦ A 1− B 1≦30%  (iii)

A 10≦40%  (iv)

B 10≦15%  (v)

10%≦ A 10− B 10≦30%  (vi)

A 10− A 1≦9%  (vii)

B 10− B 1≦4%  (viii)

wherein A 1 is an elongation obtained by the following expression:
(length under load−initial length)/(initial length)×100

wherein the length under load is a length of the leather-like sheet when a load of 8 kg/2.5 cm is put at a lower end of the leather-like sheet held vertically;
B 1 is an elongation obtained by the following expression after unloading:
(length after unloading−initial length)/(initial length)×100;

A 10 is an elongation when loaded after repeating a loading/unloading operation 9 times and obtained by the same manner as in A 1 ; and
B 10 is an elongation after repeating the loading/unloading operation 10 times and obtained by the same manner as in B 1 .

2. The leather-like sheet according to claim 1 , wherein the breaking strength in each of the machine direction and the transverse direction is 50 kg/2.5 cm or more.

3. A grain-finished leather-like sheet produced by a process comprising forming a grain layer on one or both surfaces of the leather-like sheet according to claim 1 .

4. The grain-finished leather-like sheet according to claim 3 , wherein:
a breaking strength in each of the machine direction and the transverse direction is 50 kg/2.5 cm or more,
a machine direction/transverse direction ratio of the breaking strength is 1/1 to 1.3/1, an elongation at break in each of the machine direction and the transverse direction is 80% or more,
a machine direction/transverse direction ratio of the elongation at break is 1/1 to 1/1.5, and wherein the grain-finished leather-like sheet satisfies the following properties (i) to (viii):
A 1≦40%  (i)

B 1≦15%  (ii)

10%≦ A 1− B 1≦30%  (iii)

A 10≦40%  (iv)

B 10≦15%  (v)

10%≦ A 10− B 10≦30%  (vi)

A 10− A 1≦9%  (vii)

B 10− B 1≦4%  (viii)

wherein A 1 is an elongation obtained by the following expression:
(length under load−initial length)/(initial length)×100

wherein the length under load is a length of the leather-like sheet when a load of 8 kg/2.5 cm is put at a lower end of the leather-like sheet held vertically;
B 1 is an elongation obtained by the following expression after unloading:
(length after unloading−initial length)/(initial length)×100;

A 10 is an elongation when loaded after repeating a loading/unloading operation 9 times and obtained by the same manner as in A 1 ; and
B 10 is an elongation after repeating the loading/unloading operation 10 times and obtained by the same manner as in B 1 .

5. A method of producing the leather-like sheet of claim 1 , the method comprising, sequentially, (1), (2), (3), (4), (5), and (6), or, sequentially, (1), (2), (3), (5), (4), and (6):
(1) producing a long-fiber web from composite fibers which are capable of converting into bundles comprising microfine long fibers having an average single fiber fineness of 0.5 dtex or less;
(2) producing a superposed web by folding the long-fiber web at predetermined intervals continuously and repeatedly at a folding back angle of 75° or more to a machine direction of the long-fiber web;
(3) producing an entangled nonwoven fabric by entangling the superposed web;
(4) impregnating a solution of an elastic polymer to the entangled nonwoven fabric and wet-coagulating the elastic polymer;
(5) converting the composite fibers in the entangled nonwoven fabric comprising the elastic polymer to bundles of microfine long fibers; and
(6) heat-treating a microfine long-fiber nonwoven fabric comprising the bundles of microfine long fibers while maintaining the microfine long-fiber nonwoven fabric at least in a transverse direction at a predetermined width.

6. The method according to claim 5 , wherein the folding back angle is 78 to 88° and an absolute value of a difference between a morphologic angle just before (3) and a morphologic angle immediately after (6) is 18° or less.

7. The method according to claim 5 , wherein an aqueous oil agent is provided to the entangled nonwoven fabric between (5) and (6).

8. The leather-like sheet according to claim 1 , wherein the long fibers have a length of 100 mm or more before being converted to microfine fibers.

9. The leather-like sheet according to claim 1 , wherein the web orientation angle in the leather-like sheet is 73 to 86°.

Assignees

• Makimura Masaru
• Andoh Hidekazu
• Fujisawa Michinori
• Murate Yasunori
• Ando Yoshiyuki
• Nobuto Yoshiki
• Makiyama Norio
• Kuraray Co

Inventors

• Makimura Masaru
• Andoh Hidekazu
• Fujisawa Michinori
• Murate Yasunori
• Ando Yoshiyuki
• Nobuto Yoshiki
• Makiyama Norio

Classifications

• Y10T442/2377

  Improves elasticity · CPC title

• Y10T428/24438

  Artificial wood or leather grain surface · CPC title

• D04H3/12

  with filaments or yarns secured together by chemical or thermo-activatable bonding agents, e.g. adhesives, applied or incorporated in liquid or solid form · CPC title

• D06N3/0013

  using multilayer webs · CPC title

• D04H3/016

  characterised by the fineness · CPC title