Bleaching and dyeing; fluid treatment and chemical modification – Chemical modification of textiles or fibers or products thereof – With coating – sizing – or lubricating
Reexamination Certificate
2000-08-16
2003-11-04
Gupta, Yogendra N. (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Chemical modification of textiles or fibers or products thereof
With coating, sizing, or lubricating
C008S115510, C008S115540, C008S115550, C008S115700, C008S116400, C008S120000, C428S029000, C428S096000, C428S151000, C428S156000, C428S171000
Reexamination Certificate
active
06641619
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oil tone artificial leather sheet which has a high-quality appearance, has a soft hand touch and feel equivalent to that of natural leather, and is useful in application to the manufacture of shoes, etc.
2. Description of the Background
Recently, as outdoor activities are assuming more importance as a form of recreation, shoes providing a casual feel and made of natural leather or man-made leather are becoming more popular. Oil tone materials like natural leather have a moist touch and an elegant appearance, and are in high demand for high-quality materials for shoes.
Artificial leather is also used for shoes on account of its light weightness as compared with natural leather, but due to its structure, it requires a certain surface preparation in order to give it a moist touch like the oil tone material of natural leather.
In the past, various treatments have been proposed as surface coating agents not only for artificial leather but also for synthetic leather. For example, Japanese Patent Laid-Open No. 285268/1986 discloses a method using a surface coating agent comprising a blend of polybutylene and silica with a resin having a polyurethane as its main component. Further, Japanese Patent Laid-Open No. 139877/1989 discloses a method of containing an oil-soluble surfactant in such a substance. However, in these methods, although surface touch is improved, the moist touch of oil tone natural leather cannot be reproduced.
Accordingly, there remains a need for artificial leather material which overcome these drawbacks.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a an oil tone artificial leather sheet.
After intensive studies of artificial leather sheets which had a high-quality appearance and the moist touch of oil tone natural leather, the inventors succeeded in developing an oil tone artificial leather sheet having a blend of an oily substance of viscosity 50-10,000 mPa·s at 30° C. and a supporting polymer on part or all of, i.e., on at least a portion of, a nap surface of a napped sheet comprising a non-woven fabric of microfine fibers and polyurethane existing in the non-woven fabric, wherein raised fibers comprising said microfine fibers are present in part or all of at least, i.e., at least a portion of, one surf ace and are forming the nap surface, and thereby achieved the above object.
Accordingly, the present invention provides an oil tone artificial leather sheet, comprising:
a napped sheet comprising a non-woven fabric of microfine fibers and a polyurethane in the non-woven fabric, wherein raised fibers comprising the microfine fibers are present in at least a portion of at least one surface of the sheet and form the nap surface; and
a blend of an oily substance having a viscosity of 50 to 10,000 mPa·s at 30° C. and a supporting polymer on at least a portion of the nap surface of the napped sheet.
The present invention also provides a method of making the oil tone artificial leather sheet comprising coating the napped sheet with the blend of the oily substance and the supporting polymer.
DETAILED DESCRIPTION OF THE INVENTION
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description.
In the present invention, it is particularly desirable that the supporting polymer is an olefinic elastomer or a vinyl aromatic elastomer. Suitable examples of olefinic elastomers are block copolymers comprising an ethylene polymer or an ethylene polymer block having hydrocarbon groups with 18 carbon atoms in side chains, and 5-60 mol % of units having side chains relative to the ethylene unit forming the main chain. Suitable examples of vinyl aromatic elastomers are block copolymers comprising a polymer block A comprising a vinyl aromatic compound and a polymer block B comprising a diene, or their hydrogenation products. The weight ratio of oily substance to that of the supporting polymer is preferably in the range 1:1-20:1. This range includes all specific values and subranges therebetween, such as 2:1, 5:1, 10:1, 12:1, 15:1, and 18:1.
The supporting polymer of the oily substance comprising this invention is a polymer having elastomeric properties at ordinary temperature, which, when made into a sheet of 0.5mm thickness, easily lengthens by 100% or more at ordinary temperature under an external force, but immediately recovers its original shape when the force is removed. When a powder of this polymeric elastomer is immersed in the oily substance used in conjunction with it, left for 24 hours at ordinary temperature and then subjected to natural filtration, the weight of the powder absorbs the oily substance so that it increases to 200% or more. Good results are obtained when an olefinic elastomer or a vinyl aromatic elastomer is used as the supporting polymer. Examples of such olefinic elastomers are block copolymers comprising an ethylene polymer or an ethylene polymer block having hydrocarbon groups with 1-8 carbon atoms in side chains, and 5-60 mol % of units having side chains relative to the ethylene unit forming the main chain. Examples of vinyl aromatic copolymers are block copolymers comprising a polymer block A comprising a vinyl aromatic compound and a polymer block B comprising a diene compound, or a hydrogenated block hydrogenation product obtained by hydrogenation of this block copolymer. With these supporting polymers, particularly good results are obtained from the viewpoint of retention of the oily substance.
The olefinic elastomer which is a suitable example of a supporting polymer useful in this invention will be described below.
An olefinic elastomer is a resin based on a hydrocarbon chain, and it has a segment having a glass transition point below room temperature. Examples are EPR (ethylene propylene rubber), EBR (ethylene butylene rubber) and HBR (hydrogenated butadiene rubber). The manufacturing method f or these polymers, which is well-known, requires an olefin such as ethylene, propylene, butene or octene as the main raw monomer, and if necessary, a cyclic hydrocarbon compound or diene hydrocarbon compound such as isobutylene, cyclopropene, cyclobutene, cyclopentene, cyclooctene, cyclooctadiene, butadiene, isoprene or norbornene used in conjunction. These monomers are suitably blended, and polymerization carried out by a known polymerization technique, for example, radical polymerization, anionic polymerization or cationic polymerization. Hydrogenation may be performed in some cases to enhance final physical properties, especially weatherability.
A particularly good olefinic elastomer is a copolymer of ethylene and an alpha-olefin. Examples of the alpha-olefin are propylene, butene, pentene, hexene, heptene, octene and nonene. There is no particular limitation on the polymerization method, but polymerization is usually performed in the presence of a Zieglar-Natta catalyst or a metallocene catalyst. In this case, ethylene polymers having 5-60 mol % of units containing a side chain derived from the alpha-olefin relative to the ethylene unit forming the main chain, have excellent elastomer properties and oily substance retention. There is no limitation on the molecular weight of the olefinic elastomer, but it is in the range of several 10,000 to several 100,000. Also, other monomers apart from alpha-olefins may be copolymerized in small amounts as desired. Examples of such monomers are styrene, butadiene and isobutylene, etc.
Next, the vinyl aromatic elastomer which is a suitable example of the supporting polymer comprising this invention, will be described below. Typical examples of the vinyl aromatic elastomer are polymers which generally have a styrene unit as a hard segment, and a resin part with a glass transition point below room temperature as a soft segment. The resins known as SBS (triblock copolymer comprising a styrene polymer block butadiene-polymer block-styrene polymer block), SEBS (trib
Hayashi Kohei
Nobuto Yoshiki
Yoneda Hisao
Gupta Yogendra N.
Hamlin Derrick G
Kuraray Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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