Stock material or miscellaneous articles – Composite – Of addition polymer from unsaturated monomers
Reexamination Certificate
2001-11-29
2004-07-27
Tarazano, D. Lawrence (Department: 1773)
Stock material or miscellaneous articles
Composite
Of addition polymer from unsaturated monomers
C427S257000, C156S231000, C156S230000
Reexamination Certificate
active
06767645
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a release paper. More particularly, the present invention relates to a release paper which comprises a release layer of a specified 4-methyl-1-pentene resin and which can be appropriately used in, for example, production of a synthetic leather.
BACKGROUND OF THE INVENTION
Generally, synthetic leathers are produced by first coating a release paper having a relief pattern on its surface with a base resin such as polyurethane resin in liquid form, subsequently effecting drying to thereby obtain a resin layer on the release paper, thereafter bonding a base material such as cloth to the resin layer, and finally removing the release paper. The surface of thus produced synthetic leathers is in such a condition that the relief pattern of the surface of release paper has been transferred thereto.
The release paper for use in the above production of synthetic leathers must have excellent heat resistance and release capability. Therefore, in the release paper, a 4-methyl-1-pentene polymer whose melting point is as high as about 220 to 240° C. is used as a principal component of a release layer formed on a base such as paper.
For example, a paper base overlaid with poly-4-methyl-1-pentene by extrusion laminating is used as the release paper for synthetic leather. In the production of this release paper for synthetic leather, the release layer is embossed so that desired pattern is provided on the surface of the release layer. The intended synthetic leather can be produced by casting a resin for synthetic leather over the surface of the release layer and hardening the resin.
A release paper for synthetic leather production comprising a paper base laminated with a release layer constituted of a 4-methyl-1-pentene polymer composition comprising 80 to 97 parts by weight of 4-methyl-1-pentene polymer (A) and 3 to 20 parts by weight of ethylene/ethyl acrylate copolymer (B), was proposed in Japanese Patent Laid-open Publication No. 8(1996)-25580. According to this publication, the release layer of the release paper has excellent heat resistance and wettability, so that the release paper can be appropriately used even in the production of a synthetic leather from a water soluble or water dispersible resin.
There has been such a problem that, when the release paper is repeatedly used in the production of a synthetic leather or the like, the release paper curls into cylindrical form. Upon curling of the release paper, the work efficiency is poor in the reuse of the release paper, and, when forced elimination of curling is intended, the surface of the release paper may suffer from flaw or microcracking to thereby cause the reuse thereof to be difficult. The greater the thickness of the release layer of the release paper, the more serious the tendency toward these problems.
Therefore, there has been a strong demand for the development of a repeatedly usable release paper which is excellent in heat resistance and exhibits less curling tendency in repeated use and which exhibits a high bonding strength between resin and paper.
OBJECT OF THE INVENTION
It is an object of the present invention to provide a release paper which is excellent in heat resistance and exhibits less curling tendency in repeated use, which exhibits a high bonding strength between resin and paper and is excellent in durability, and which is suitable for use in, for example, production of a synthetic leather.
SUMMARY OF THE INVENTION
The release paper of the present invention comprises:
a paper base laminated with a release layer,
the release layer comprising a 4-methyl-1-pentene resin being a copolymer of 4-methyl-1-pentene and an &agr;-olefin other than 4-methyl-1-pentene wherein the &agr;-olefin is contained in a proportion of 6 to 8% by weight.
With respect to the release paper of the present invention, it is preferred that the &agr;-olefin have 10 to 20 carbon atoms. Preferably, the release paper is for use in production of a synthetic leather.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
The release paper of the present invention comprises a paper base laminated with a release layer. Only one side of the paper base may be laminated with the release layer. Alternatively, both sides of the paper base may be laminated with the release layer.
<Release Layer>
The release layer as a constituent of the release paper of the present invention comprises a 4-methyl-1-pentene resin being a copolymer of 4-methyl-1-pentene and an &agr;-olefin other than 4-methyl-1-pentene wherein the &agr;-olefin is contained in a proportion of 6 to 8% by weight.
The &agr;-olefin other than 4-methyl-1-pentene for constituting the 4-methyl-1-pentene resin can be, for example, any of &agr;-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicocene. At least one of these can be employed. Among them, an &agr;-olefin having 10 to 20 carbon atoms is preferred. In particular, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicocene are especially preferred.
It is preferred that the 4-methyl-1-pentene resin be a copolymer of 4-methyl-1-pentene and an &agr;-olefin having 2 to 20 carbon atoms, especially 10 to 20 carbon atoms, from the viewpoint that the obtained release paper is highly flexible and is excellent in heat resistance.
In the 4-methyl-1-pentene resin for constituting the release layer in the present invention, the &agr;-olefin is contained in a proportion of 6 to 8% by weight, preferably 6 to 7% by weight.
When the &agr;-olefin content of the 4-methyl-1-pentene resin is as low as less than 6% by weight, the crystallinity and orientation coefficient of the 4-methyl-1-pentene resin tend to exhibit unfavorably large values. When the release paper including the release layer constituted of such 4-methyl-1-pentene resin is used in the production of a synthetic leather, the release layer may unfavorably be shrunk by heating in the process for producing the synthetic leather to thereby cause the release paper to curl.
On the other hand, when the &agr;-olefin content of the 4-methyl-1-pentene resin is as high as more than 8% by weight, the heat resistance of the release layer resin may be unsatisfactory. When the release paper including the release layer constituted of such resin is used in the production of a synthetic leather, the embossed pattern provided on the release layer may unfavorably be flowed by heating in the process for producing the synthetic leather to thereby cause the repeated use of the release paper to be infeasible.
When the &agr;-olefin content of the 4-methyl-1-pentene resin is in the range of 6 to 8% by weight, these problems can favorably be avoided to thereby enable the repeated use of the release paper.
With respect to the 4-methyl-1-pentene resin for use in the present invention, it is preferred that the melt flow rate (MFR) thereof as measured under a load of 5.0 kg at 260° C. according to ASTM D1238 be in the range of 1 to 400 g/10 min, especially 20 to 300 g/10 min, and still especially 50 to 200 g/10 min. The use of such 4-methyl-1-pentene resin is preferred from the viewpoint that laminating can be efficiently conducted at a high speed to thereby enhance the productivity of release paper, that a uniform thickness can be realized and the release layer can be free from cracking, and that a release paper which is excellent in the bonding strength between the release layer and the paper base layer can be easily produced.
In the present invention, the 4-methyl-1-pentene resin for constituting the release layer can be produced by copolymerizing 4-methyl-1-pentene and at least one of the above &agr;-olefins according to known processes.
In the present invention, the 4-methyl-1-pentene resin may contain various additives customarily incorporated in polyolefins according to necessity in an amount not detrimental to the object of the present invention. Also, the 4-methyl-1-pentene resin may co
Fukumoto Kenichi
Noritomi Katsumi
Birch & Stewart Kolasch & Birch, LLP
Mitsui Chemicals Inc.
Tarazano D. Lawrence
LandOfFree
Release paper does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Release paper, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Release paper will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3258600