Patent Grant
8192846
This patent application is the National Stage of International Application No. PCT/EP2008/000171, filed Jan. 11, 2008, that claims the benefit of European Application No. 07000622.6, filed Jan. 12, 2007, the entire teachings and disclosure of which are incorporated herein by reference thereto.
The present invention relates to a composition for decorative surface coverings and to a manufacturing process for said compositions.
Synthetic decorative surface coverings such as floor coverings are generally based on PVC and have been known for decades. The key features of this kind of materials are essentially abrasion resistance (resistance to scratches), dimensional stability, absence of creeping, low smell, stain resistance and tear resistance.
In the last years, environmental issues on PVC coverings such as VOC (Volatile Organic Compounds) release, plasticizers and thermal stabilizers toxicity has motivated the floor covering industry to put search efforts on PVC alternatives. These alternative compositions should nevertheless preferably be convertible on conventional PVC equipment in particular on PVC extruders.
Vulcanisable standard rubber floor covering compositions generally comprise less than 30 wt % rubber internally mixed with about 60 wt % of fillers and less than about 10 wt % of curing agents and processing aids. Rubber floor coverings are known to be less tear and stain resistant than PVC floorings. Additionally, conventional PVC equipment cannot manage these compositions.
Document WO 97/010298 discloses a flooring material based on crosslinked polyolefin's and unsaturated silane compounds. The floor covering composition comprises various additives and is free of organic fillers.
Document WO 2006/005752 discloses a large variety of possible compositions combining a series of elastomers, thermoplastics and a high styrene resin cured with conventional curing systems like TBBS, ZBEC, CBS, sulphur, stearic acid and zinc oxide. The composition disclosed in the examples cannot be extruded on conventional PVC extruders, it sticks on the steel belts and can only be worked in a steel belt press in combination with silicon release paper. Furthermore, the obtained granules have a strong tendency to agglomerate in the transport containers. An additional drawback is the absence of flame retardant filler and the high production cost.
US 2002/0168500 A1 discloses an electrically conductive floor covering using a combination of a high styrene resin (HSR) and SBR rubber together with high amounts of carbon black. This composition cannot be worked on conventional extruders, making rubber equipment necessary.
EP 1 361 249 A2 discloses a substantially halogen-free thermoplastic elastomer composition for decorative surface coverings comprising a dynamically vulcanized blend of epoxydized rubbers such as natural rubber, EPDM, NBR and SBR, ionomers and diluent polymers. In this composition the use of SBS, SBR or HSR with specific styrene contents are not disclosed and rubber equipment is used for the mixing of the different ingredients.
The present invention aims to provide an improved composition for a substantially halogen-free decorative surface covering which overcomes the drawbacks of the prior art and which is convertible on conventional PVC extrusion equipment.
The present invention discloses a decorative surface covering obtainable by a vulcanisable composition, said composition comprising:
According to particular embodiments, the present invention may comprise one or a combination of any of the following characteristics:
The present invention further discloses a process for manufacturing the decorative surface covering of the invention comprising the following steps:
In particular embodiments of the present invention, the step of dry mix comprising the various colour batches comprises the adding of additionally virgin styrene butadiene styrene granules.
Advantageously, an additional polyurethane-based top coating is applied as a finish on the decorative surface covering.
Decorative coverings include any design covering that provide an enhanced appearance to a substrate. These can include wall and floor coverings as well as ceilings.
The expression “substantially halogen-free” has to be understood as devoid of any halogen-containing polymer. This does not exclude the presence of impurities or additives in a concentration of less than 1%.
The expression “polymer component” has to be understood as a distinguishable polymer family which is part of the global composition such as the filler, vulcanisation system and additives.
The composition of the decorative surface covering of the present invention is in its final state a vulcanised composition wherein all the vulcanisable components are at least partly vulcanised and wherein a vulcanisation system has reacted and does not any longer exist as such. Therefore the present invention discloses a vulcanisable composition which is the precursor of the vulcanised finished decorative surface covering.
One of the key advantages of the invention is the processing of the mixture at the extruding step which is part of a conventional PVC process. Indeed, the usual rubber formulations need to be performed through internal mixers due to the high viscosity below the vulcanisation temperature. A conventional rubber could never be processed using an extruder at temperatures around 120° C., i.e. at temperature ranges that would avoid vulcanisation. The role of the thermoplastic material (thermoplastic rubbers and optionally ionomers) in the composition of the invention is to lower the viscosity of the mix at temperatures below the vulcanisation temperature, and thus to allow the processing through a conventional extruder.
Another crucial step of the process of the invention is the grinding or granulating and the blending of granulates. Actually, these steps are only possible if the material after extrusion and cooling does not remain tacky. This is the reason why thermoplastic elastomers were added to the formulation. Thermoplastic elastomers and optionally ionomers are needed to allow the processing through conventional PVC equipments and are selected from the range of those which may enhance the final characteristics of the covering; for instance ionomers can optionally improve the abrasion resistance while high styrene content styrene butadiene copolymer will improve the stiffness of the covering, i.e. a key feature for an easy installation of the floor covering.
The percentage of each component will be a fine balance between the processing, the requested features of the covering and the overall price of the whole formulation.
Definitions and Raw Material Description
1st Polymer Component: Block Copolymer of SBS
SBS or styrene butadiene styrene is considered as a thermoplastic elastomer that can be converted in extrusion equipments for thermoplastics.
The following materials fall under this definition and present possible polymer examples for the present invention:
2nd Polymer Component: SBR or NBR
The following materials fall under this definition and present possible polymer examples for the present invention:
Nitrile Butadiene Rubber: NBR
High Styrene Content Styrene Butadiene Copolymer: HSR
In the case of HSR, a high styrene content copolymer of butadiene and styrene is meant. These molecules are close to SBR but contain generally at least 55 wt % of bounded styrene.
The following materials fall under this definition and present possible polymer examples for the present invention:
Ionomers
The ionomer examples according to the present invention are at least partially neutralized acid copolymers or terpolymers.
Filler (Clays, Aluminium Trihydrate, Carbonates, . . . )
Vulcanisation Systems
Additives
The first and the second dry mix are fed into a double screw extruder Werner & Pfleiderer ZSK and mixed with various pigments at a material temperature below 120° C. and subsequently granulated and cooled by air to room temperature.
The various coloured batches are then mixed again according to the design requests.
The mixed colour batches are then fed into a double belt press and heated up to 170° C. to be vulcanised.
Remark: This composition exhibits good processing ability and very good scratch resistance (see Table 1).
This example was performed in the same way as Example 1 except that the polymer proportions were modified, in particular the SBS content was heavily decreased and the ionomer content heavily increased:
This example was performed in the same way as Example 1 except that the polymer proportions were modified, in particular the SBS content was heavily increased and the SBR content heavily decreased:
This example was performed in the same way as Example 1 except that the polymer proportions were modified, in particular a low proportion of HSR were tested:
This example was performed in the same way as Example 1 except that the polymer proportions were modified, in particular a high proportion of HSR and a low proportion of SBR were tested:
This example was performed in the same way as Example 1 except that the polymer proportions were modified, in particular a very high proportion of ionomer and a low proportion of SBR were tested:
This example was performed in the same way as Example 1 except that the polymer proportions were modified, in particular a very low proportion of an alternative ionomer and a lower proportion of SBR were tested:
This example was performed in the same way as Example 1 except that the polymer proportions were modified, in particular a lower proportion of SBS and a lower proportion of HSR combined with a higher proportion of SBR were tested:
This example was performed in the same way as Example 1 except that the polymer proportions were modified, in particular a high proportion of ionomer and a lower proportion of SBR were tested:
This example was performed in the same way as Example 1 except that the polymer proportions and nature were modified, in particular a high proportion of ionomer and a low proportion of NBR were tested, the NBR replacing the former SBR:
This example was performed in the same way as Example 1 except that the polymer proportions were modified, in particular a very high proportion of NBR and a lower proportion of SBS together with a lower proportion of ionomer were tested:
Example 12 is identical to Example 1 except that the quantity of filler was increased and the nature of the filler was modified:
In this example, the proportion of polymers is reduced proportionally to the increase of filler.
Remark: Not as good in processing ability and in scratch resistance.
Example 13 is identical to Example 1 except that the global filler amount was reduced:
In this example the proportion of polymers is increased proportionally.
Remark: Not as good in processing ability and in scratch resistance.
Example 14 is identical to Example 1 except that Kralex 1507, Kaucuk, containing 23.5 wt % styrene has been replaced by Europrene 1739 containing 40 wt % of styrene.
Remark: Correct processing ability and acceptable properties
This example was performed in the same way than Example 1 except that the polymer proportions were modified, in particular a lower proportion of SBS and a lower proportion of HSR combined with a higher proportion of SBR were tested:
This example was performed in the same way than Example 1 except that the Ionomer was excluded:
This example was performed in the same way than Example 1 except that the polymer proportions were modified and the Ionomer was excluded:
This example was performed in the same way than Example 1 except that the polymer proportions were modified and the Ionomer was excluded:
Test Methods
Examples 1 to 15 have been tested according to partially specific testing methods of the inventor that can be shortly described as follows:
Scratch Resistance
The apparatus with the scratching tool is placed over the sample so that a wagon can be pulled across the surface. The applied force starts with 0.5N and increase 0.5N each time until a scratch appears. The results are expressed as load (N) resulting in a scratch that can be seen corresponding to the first value in Table 1 and load (N) resulting in a scratch that can be felt corresponding to the second value in Table 1.
Stiffness
The stiffness of a material is measured with a Clash & Berg stiffness tester. The sample is fixed by specimen grips, put in a water container and subjected to rotation. One side of the sample is under the subject of torsional moment. The angle is recorded after the test.
Friction
Friction is measured with a modified Tortus friction tester. Instead of using the measuring foot, a sled is fastened to the machine by a line. The force required to drag the sled over the surface of the sample with the motor of the machine is recorded as the friction value.
Stain Resistance
The test is used for determining the stain resistance against water-, alcohol- and oil-soluble colorants of a flooring sample. Put two drops of each staining agent of the surface and cover each staining agent with a watch glass. Remove the watch glasses after the test and clean the surface with the cleaning agents. The remaining stains are visually evaluated.
Castor Chair
The test is based on EN 425 for determining the change of appearance and stability of a flooring material. The sample is fixed on the moving board by using adhesive, but by not fixing a certain area (10*20 cm), dimensional changes can appear when the material expands. About 25.000 rotations are performed on each sample. Any change of appearance or dimensional changes are recorded.
| Number | Date | Country | Kind |
|---|---|---|---|
| 07000622 | Jan 2007 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2008/000171 | 1/11/2008 | WO | 00 | 5/8/2009 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2008/083973 | 7/17/2008 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20020168500 | Graab et al. | Nov 2002 | A1 |
| 20060229411 | Hatfield et al. | Oct 2006 | A1 |
| Number | Date | Country |
|---|---|---|
| 1 361 249 | Nov 2003 | EP |
| 1 616 923 | Jan 2006 | EP |
| 2 168 362 | Jun 1986 | GB |
| WO 9710298 | Mar 1997 | WO |
| WO 2006005752 | Jan 2006 | WO |
| WO 2006107763 | Oct 2006 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20100003527 A1 | Jan 2010 | US |
