Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2000-12-19
2001-12-18
Foelak, Morton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S079000, C521S081000, C521S143000, C521S144000, C521S150000, C521S051000
Reexamination Certificate
active
06331576
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a foam skin of cross-linked rubbery soft olefin resin whose surface is decorated likely as a leather or a cloth having silver like tone, that is, the surface of which is decorated using a mold which has embossed pattern or network pattern. More in detail relates to the rubbery olefin type cross-linked foam with soft resin surface layer having good heat resistance, soft touch and rubbery elasticity.
DESCRIPTION OF PRIOR ART
In general, the foam whose surface is decorated was existent. Among the olefin type foam, polyethylene foam can be decorated by an embossed type mold. However, the surface layer of surface part is melted, re-solidified and becomes fine (because it is high crystalline type resin). And the feeling of it is dry and rough and it is difficult to obtain a feeling of leather like or cloth like. To provide a finer and deeper embossed pattern on the surface, it is necessary to intensify the heat melting condition of the surface, however, since the heat resistance of it is low (because the melting point of polyethylene is low, 100 to 120° C.), shrinking ratio by heating is big and the embossing by good dimensional stability is impossible.
The foam composed by a copolymer of ethylene.vinyl acetate have a little softness, however, the heat resistance of it is inferior to that of polyethylene foam, and has a tendency to be hardened by the heating of emboss processing. Therefore, said foam is not a suited material to provide a fine and deep emboss pattern on it.
Polypropylene type foam has a good heat resistance, and therefore has a merit that the ordinary type of molding technique can be applied. However, it is a hard material, and when the surface is decorated, the surface becomes too fine and the impression of hard is emphasized.
And if the surface of said kinds of foams whose surface is decorated are heated to the temperature higher than the melting point to improve the transcribed ratio of grained pattern at the emboss processing, it looses it's cushion feeling and becomes creased when it is bent, and is far from the feeling of leather like or cloth like, because the viscosity of these materials falls down suddenly and the permanent deformation of foam layer under the decorated surface becomes big at the emboss processing (pressed),
As mentioned above, the olefin foam whose surface is decorated was developed and on the market, however the applications of it are for example, a surface material of mold for an engineering works or inside materials for waterproof sheet, and cannot be used as the surface materials for interior decorations.
Meanwhile, as olefin type foam which has soft touch and rubbery elasticity, an olefin type rubber foam which uses EPR or EPT as a starting materials can be mentioned, which has a good feeling as a foam. However, since this rubber foam is rubber foam which has rubber elasticity caused by a bridged material of non-crystalline rubber molecular, is a very difficult materials for surface decoration (embossing) processing. Further, since the shrinking ratio of it by heating is high, the productivity as the materials of surface sheet in a case of after decoration of foam, and is a problem.
Rubber foams except olefin type, especially in a case of chloroprene rubber foam which has excellent soft feeling, besides the ordinary problems which EPR or EPT foams have, chlorine type toxic gas generates at the heating of after decoration process, which is a serious environmental problem for the corrosion of a equipment and for a human body.
As the method to solve these mentioned problems and to obtain a surface decorated olefin type foam which has good heat resistance, softness and rubbery elasticity, methods disclosed in Japanese Patent Laid Open Publication 57-20334 or in Japanese Patent Laid Open Publication 2-258247 are well-known. These methods are the method to decorate the surface by laminating a heat plastic elastomer sheet having good heat resistance, softness and rubbery elasticity on above-mentioned foams. Therefore, in these methods, plural kinds of materials such as foam, surface layer sheet and adhesive are required at need, and the manufacturing process is complicated.
Meanwhile, the method disclosed in Japanese Patent Laid Open Publication 6-278220 is the method to perform a specific grained pattern directly on soft rubber foam by heating the sliced surface of rubber foam whose base material is high crystalline rubber using heat roller. This method is applying the deflecting agglutination feature at hot working of high crystalline rubber and therefore the surface grained pattern is special, however, has problems at surface toughness and heat resistance.
OBJECT OF THE INVENTION
This invention solves the problems accompany to the prior art, and the object of this invention is to provide a new foam material which can be decorated and can be used as an interior finishing material. This material not only has a good heat resistance, softness and rubbery elasticity, but also the surface of which has good heat treatment processability, and the object of this invention is to provide a surface decorated rubbery soft olefin resin cross-linked foam like surface layer.
BRIEF DESCRIPTION OF THE INVENTION
The present invention provides a material to be used as a material for surface layer by an emboss process. Said material is rubbery and also has property of plastics (thermo-plastic), and uses properly cross-linked olefin type resin foam.
The important point of this invention is that a surface decorated foam skin of cross-linked rubbery soft olefin resin, comprising rubbery soft olefin resin, characterizing by having average cell diameter of 50 to 400 &mgr;m, a degree of crystallinity of 5 to 40% and a hysteresis loss of 35% or lower. Further, said surface decorated foam skin of cross-linked rubbery soft olefin resin is desirably characterized as the gel fraction is in the region of 20 to 98%, 50% compressive stress is in the region of 0.3 to 1.5 kg/cm
2
, 90° C. hot dimensional shrinking ratio is smaller than 5%, and the transcribed ratio of grained pattern is smaller than 40%.
That is, the average cell size of the foam like surface layer composed by rubbery soft olefin resin of this invention is 50 to 400 &mgr;m, desirably 50 to 200 &mgr;m, degree of crystallinity is 5 to 40%, desirably 5 to 35%. When the degree of crystallinity is in this region, the foam like surface layer of this invention shows sufficient restorability, good at decorative processing and generates elastic cushioning property. And by making hysteresis loss smaller than 35%, desirably smaller than 30%, and further by making the transcribed ratio of grained pattern smaller than 40%, it becomes possible to provide the surface decorated rubbery soft olefin resin cross-linked foam like surface layer which can be easily decorated by surface heat treatment of a foam maintaining good heat resistance, without spoiling softness and rubbery elasticity.
DETAILED DESCRIPTION OF THE INVENTION
Details of the invention are illustrated as follows.
As the rubbery soft olefin resin which composes this cross-linked foam, olefin type copolymer rubber or the mixture of crystalline polyolefin resin and olefin type copolymer rubber can be used.
Said mixture of crystalline polyolefin resin and olefin type copolymer rubber has a good rubbery elasticity, and when the mixture is used as the rubbery soft olefin resin, the rubbery soft olefin resin cross-linked foam like surface layer which generates excellent restorability by rubbery elasticity can be obtained at each molding process.
The olefin type copolymer rubber of this invention is an amorphous elastic copolymer whose contents of &agr;-olefin of carbon number 2 to 20 is smaller than 50 mol % or an elastic copolymer whose degree of crystallinity is smaller than 50%, that is, non conjugated copolymer by non crystalline &agr;-olefin composed by more than two kinds of &agr;-olefin, and more than two kinds of &agr;-olefin.
As a concrete example of such kind of olefin ty
Ichimura Shigeki
Kusakawa Koichi
Foelak Morton
NHK Spring Co Ltd
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