Plastic and nonmetallic article shaping or treating: processes – Random variegated coloring during molding
Reexamination Certificate
1999-06-28
2001-06-26
Tentoni, Leo B. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Random variegated coloring during molding
C264S143000, C264S162000
Reexamination Certificate
active
06251321
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an elastomer floor covering. In particular, it relates to a homogeneous floor covering of cross-linkable, elastomer material, having a directionless pattern. A manufacturing process is also specified.
DESCRIPTION OF RELATED ART
European Patent A1 0 512 197 describes a floor covering of the species, which is completely free of trapped air. The manufacturing process is characterized in that, using a short screw-type extruding machine including an attached perforated disk, moldings having a size of 1 to 2 mm are continuously produced from two or more varicolored, vulcanizable elastomer materials by knocking off the emerging strands.
These moldings are passed through the gap of a two-roll calender under a constant line pressure, the calender having horizontally arranged rolls capable of being heated and cooled, a homogeneous band being formed, which is vulcanized to form a ready-made floor covering. To keep the line of pressure in the roll nip as narrow as possible, a very low diameter/length ratio of 1:3.5 is preferred.
Using this process, floor coverings having a thickness of approximately 2 mm can only be made in a limited width. In the recommended diameter/length ratio of 1:3.5 for the calender, the width of 1250 mm specified in the citation already requires a roll diameter of 370 mm, given a length of 1300 mm. It has been found that, in the manufacture of a 2 mm thick web, such slim rolls bend away from each other in the middle of their axial extent by up to 1 mm and more. This effect intensifies considerably in response to an increasing roll length, or web width, given a constant roll diameter.
Consequently, the resulting web has a thickness, of over 2.8 mm in its corresponding central surface area, and only the areas near the edges have the desired calibration thickness of 2 mm.
An alternative to this line pressing process is to process the material flat, for example, in a band molding press. European Patent B1 0 046 526 describes such a process, which has the advantage of an exactly equal pressing pressure in all surface areas, and consequently, the possibility of manufacturing webs having a uniform thickness.
In the process, a raw material layer of spread-out thermoplastic particles is continuously compressed flat at 160° C. to 220° C. and welded together, and is subsequently cooled down and pressed off at an unchanging pressure. In this context, the web width is dependent only on the width of the molding press.
If one tries to apply this method—described for thermoplastic materials—to vulcanizable, elastomer materials for floor coverings, webs are produced whose elongation at break, according to DIN 53 504, has values of only 20 to 30%. Such low elongations, however, are inadequate for floor coverings since they must very often be laid on uneven sub-floors and against edge areas, the floor coverings having to adapt to uneven areas and imprecise fits through certain elongation properties so as to avoid destruction.
However, elastomer materials are always to be given preference since, in contrast to thermoplastic materials, they exhibit a resistance to cigarette burns.
SUMMARY OF THE INVENTION
The object of the present invention is to specify a homogeneous floor covering of cross-linkable, elastomer material, having a multicolored, directionless pattern, which
in the case of widths of 1 m to 2 m, exhibits only an insignificant change in thickness (maximally 5%) over its entire surface,
has a thickness of 1.5 to 3.5 mm,
minimum elongation of 60% according to DIN 53 504.
A further object of the present invention, is to specify a continuous manufacturing process, making it possible to produce such a floor covering economically.
The property “homogeneous” is defined for floor coverings according to DIN 16 850: “Homogeneous elastomer coverings, composed of a layer or a plurality of layers of equal composition. They have a multicolored, continuous pattern, or a continuous, uniform color.”
This objective is achieved according to the present invention by using a homogeneous floor covering of cross-linkable, elastomer material, having a multicolored, directionless pattern, and having the properties required by the object of the invention, the floor covering, with respect to its total weight, containing 3 to 20 per cent by weight of a copolymer of ethylene including at least one comonomer belonging to the group of
vinyl esters of saturated carboxylic acids having up to 4 C-atoms in the acid group,
unsaturated mono- or dicarboxylic acids,
esters of unsaturated mono- or dicarboxylic acids having up to 8 C-atoms in the alcohol portion,
&agr;-olefins having 4 to 10 C-atoms.
In this context, the ethylene content of the copolymer must be 40 to 95 per cent by weight, the comonomer content 5 to 60 per cent by weight. The melt-flow index of the copolymer must lie between 0.1 and 50.
DETAILED DESCRIPTION OF THE INVENTION
Copolymer proportions of 3 to 10 per cent by weight turned out to be particularly advantageous, compared to ones having higher copolymer proportions, since then, due to the slight adhesive quality, the mixture can be processed more favorably on the rolls. In addition, the properties of the ready-made floor covering are not substantially affected; copolymer proportions higher than 10 per cent by weight can cause, for example, a worsening of the fire resistance.
The floor covering can be essentially in two embodiments: In the one case, the granular particles forming it have a single color in and of themselves; in the other case, they have a colored pattern in and of themselves. The visual effect of the surface is a little quieter in the latter variant while the alternative conveys a livelier picture of the surface.
The manufacture of the floor covering according to the present invention is carried out in a generally known manner in that, first of all, granular material particles are produced from unvulcanized elastomer material, the particles differing from each other in color, and also being able to have non-homogeneous colors in and of themselves. To this end, corresponding, varicolored rubber mixtures are produced independently of each other, formed into strands using extruding machines, and subsequently granulated into grain sizes of up to 3.0 mm.
Then, analogously to European Patent B1 0 046 526, at least two granular materials differing in color are spread on a band-shaped, horizontally moving carrier. Such carriers can be composed of release paper, steel band, or polytetrafluoroethylene band, and must never adhere to the particles.
The compressing and vulcanization are carried out in a band molding press appropriate for the width of the floor covering to be produced, at 160 to 180° C. and at a pressure of 3 to 30 N/mm
2
. Subsequently, the reverse side of the resulting web is polished for the sake of improving the gluing capability.
Essential to the present invention of this process is that, with respect to the total weight of the materials to be processed, 3 to 20 per cent by weight of a copolymer of ethylene including at least one comonomer are mixed with the unvulcanized rubber mixtures prior to their processing.
Suitable comonomers include
vinyl esters of saturated carboxylic acids having up to 4 C-atoms in the acid group,
unsaturated mono- or dicarboxylic acids
esters of unsaturated mono- or dicarboxylic acids having up to 8 C-atoms in the alcohol portion,
&agr;-olefins having 4 to 10 C-atoms.
The ethylene content of the copolymer is 40 to 95 per cent by weight, the rest is comonomer, and the melt-flow index of the copolymer must lie between 0.1 and 50.
Using copolymer proportions of 3 to 10 per cent by weight reduces the adhesive quality of the material during processing, and improves the fire resistance and mechanical resilience of the finished product.
With regard to the alternatives of creating the floor covering from granular material particles which have either a single color in and of themselves or a multicolored pattern in and of themselves, corresponding procedures are known to a worker skilled in the
Graab Gerhard
Heckel Klaus
Kuhl Hans-Michael
Carl Freudenberg
Kenyon & Kenyon
Tentoni Leo B.
LandOfFree
Process of making a homogeneous floor covering does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process of making a homogeneous floor covering, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process of making a homogeneous floor covering will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2482065