Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
1999-01-19
2001-05-22
Chen, Vivian (Department: 1773)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S195100, C428S203000, C428S204000, C428S212000, C428S213000, C428S215000, C428S216000, C428S480000, C428S483000, C428S413000, C428S423700
Reexamination Certificate
active
06235374
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a polyester film for decorative sheets. The decorative sheet used herein generally means a decorative material (surface material) attached to the surface of a substrate for various products such as furnitures, building components or household appliances and provided on a surface thereof with a picture-printed layer. Whereas, the decorative plate used herein generally means a building material (surface material) comprising at least a film layer and a picture-printed layer which are successively laminated on the surface of a substrate, and usually dealt as an independent commercial product. Accordingly, the film layer and the picture-printed layer laminated on the surface of the substrate of the decorative plate are constituents of the decorative sheet.
As a sheet material (film) interposed between the substrate and the picture-printed layer of the decorative plate or used in the decorative sheet, polyvinylchloride resin sheets have been most generally used. However, in the case where the polyvinylchloride resin sheet is used, there arise such problems that a plasticizer blended in the sheet is migrated to an adjacent adhesive layer, resulting in deteriorated adhesion between the sheet and a substrate, and that the polyvinylchloride resin sheet suffers from elongation or shrinkage upon heating due to low thermal dimensional stability thereof, thereby causing wrinkles thereon. Further, it has been reported that the polyvinylchloride sheet generates a chlorine gas upon burning, thereby causing sources of acid rain or dioxin. In consequence, it has been strongly demanded that decorative plates or decorative sheets should be produced without using the polyvinylchloride resin sheet from a standpoint of environmental protection.
On the other hand, since the decorative plates and the decorative sheets are used as a surface material, picture patterns having a high design value are usually formed on a surface thereof. Therefore, it is extremely important to control color tones of the decorative plate or the decorative sheets in order to obtain appropriate contrasts between the picture patterns or delicate contrasts of shade and shadow thereon.
Meanwhile, since the decorative plates and the decorative sheets are used as surface materials, it is inevitable that these plates and sheets come into contact with tip ends of cleaners, fingernails or toenails, etc., so that the surfaces thereof sometimes become damaged. Especially when the surfaces of the decorative plates or the decorative sheets undergo severe contact, scratch or abrasion, much larger damages are caused thereon, so that a surface or an inside of a underlying film layer tends to be exposed to the surfaces of the decorative plates or the decorative sheets. In such a case, when a color tone of the film layer is different from that of a printed layer provided on the surface of the film layer, the damaged portions are remarkably contrasted with surrounding portions due to the difference in color tone therebetween, thereby causing severe damage to a design value of the surfaces of the decorative plates or the decorative sheets.
Also, in the production of polyester films, there have been caused film scraps trimmed or separated off, e.g., from edge portions of biaxially-stretched films because these edge portions are unsuitable as commercial products. The film scraps are formed into pellets and then re-used as reclaimed polyester. The blending percentage of the reclaimed polyester to virgin polyester is about 3 to about 70% by weight though it is varied depending upon types of films to be produced or an aimed production efficiency. Accordingly, in the case where the above-mentioned reclaimed polyester is used for the production of polyester films, it becomes possible to obtain inexpensive decorative plates or decorative sheets using the polyester film as an alternate material of polyvinylchloride.
However, the reclaimed polyester obtained from the production process of color pigment-containing polyester films which are used as films for decorative plates or decorative sheets, suffers from considerable change in color tone during reclaiming process therefor before being formed into pellets. Therefore, when such a reclaimed polyester is mixed with virgin polyester, the color tone of the resultant polyester film is affected in a large extent.
As a result of the present inventors' earnest studies, it has been found that in use for a decorative sheet comprising at least a picture-printed layer and a film layer which will be successively laminated on a substrate thereof, by adjusting a color difference between the film layer and the picture-printed layer to a specified value, or by constituting the film layer from at least one layer and at least one other layer and adjusting a color difference between the layer and the other layer to a specified value, the above problems can be solved. The present invention has been attained by the above findings.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a polyester film for decorative sheets which can maintain a high design value even when a picture-printed layer thereof suffers from dents or scratches.
It is another object of the present invention to provide a color pigment-containing polyester film for decorative sheets which can reduce costs of raw materials by blending a reclaimed raw material therein, and can maintain a constant color tone even when such a reclaimed raw material is blended.
To accomplish the aims, in the first aspect of the present invention, there is provided a polyester film for a decorative sheet which sheet comprises a picture-printed layer (B) and the said polyester film (A) laminated on a substrate,
the said polyester film containing a color pigment in an amount of 0.1 to 30 weight % based on the weight of the said polyester (A), and
the said polyester film having a color tone which satisfies the color difference &Dgr;E* between the said polyester film (A) and the picture-printed layer (B), which is represented by the following formula (1), of not more than 50.
&Dgr;E*={(L*A−L*B)
2
+(a*A−a*B)
2
+(b*A−b*B)
2
}
½
(1)
wherein L*A, a*A and b*A represent color tone values of the polyester film (A) in CIELAB color determination system; and L*B, a*B and b*B represent color tone values of the picture-printed layer (B) in CIELAB color determination system.
In the second aspect of the present invention, there is provided a polyester film for a decorative sheet which sheet comprises a picture-printed layer (B) and the said polyester film laminated on a substrate, which polyester film comprises at least one film layer (A1) and at least one film layer (A2) and is produced by a co-extrusion method,
the said at least one film layer (A1) and the said at least one film layer (A2) satisfying the following requirements (i) and (ii):
(i) the said at least one film layer (A1) comprising polyester containing virgin polyester in an amount of not less than 90% by weight, whereas the said at least one film layer (A2) comprising 10 to 70% by weight of reclaimed polyester obtained from a color pigment-containing polyester and 30 to 90% by weight of virgin polyester; and
(ii) the color difference &Dgr;E′ between the said at least one film layer (A1) and the said at least one film layer (A2), which is represented by the following formula (3), being not more than 5.0.
&Dgr;E′={(Lm−Ls)
2
+(am−as)
2
+(bm−bs)
2
}
½
(3)
wherein Ls, as and bs represent color tone values of the film layer (A1) in Hunter's color determination system; and Lm, am and bm represent color tone values of the film layer (A2) in Hunter's color determination system.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is explained in detail below. The term of “polyesters” used herein means ester group-containing polyesters which are produced by the polycondensation of dicarboxylic acid
Miki Takatoshi
Yoshihara Kenji
Chen Vivian
Conlin David G.
Dike Bronstein Roberts & Cushman
Mitsubishi Polyester Film Corporation
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