AU2001237498B2 - Method for producing an anti-slip floor covering and resulting novel type of covering - Google Patents

Abstract

The invention concerns a method for producing an anti-slip floor covering comprising a plasticized PVC base structure, reinforced or not with a textile core, associated with a surface covering wherein are inlaid particles (10) providing the assembly with anti-slip properties. The invention is characterised in that, the method for producing said surface covering consists in: depositing on the upper surface of the base complex (1) a PVC plastisol layer (2) which is pre-gelled by heat treatment; continuously coating the pre-gelled plastisol (1) with a thermosetting powder layer (7) and subjecting the whole assembly to heat treatment (8) to form a continuous film (9) whereon, likewise continuously, while it is still in liquid phase, are deposited silicon carbide particles (10) or the like; then passing the resulting covering in a warm air furnace (11), leading to complete gelling of the plastisol and crosslinking of the surface film as well as the entrapment of the particles in said surface film (9), then grinding down and delivering the assembly.

Description

P:\WPDOCS\LMD\Frd Schilling~speificaions\77297S0spe.doc-l12/05 -1t METHOD FOR PRODUCING AN ANTISLIP FLOOR COVERING AND RESULTING NOVEL TYPE OF COVERING 00 Technical field 8 The present invention relates to an improved method for producing a thermoplastic nonslip floor covering and to the novel type of covering obtained by such a method.

Prior art Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

It has been proposed for a very long time to produce flexible nonslip floor coverings made of plastic.

In general, such coverings, sold by the applicant under the name "TARASAFE", consist of a plasticized PVC base structure reinforced with a glass-fiber mesh/nonwoven complex and covered on its visible face with a surface sheet, also made of plasticized PVC, in which solid mineral particles, such as silicon carbide, corundum, quartz, or organic particles, such as cork, are encrusted.

The nonslip surface layer may be produced either continuously with the manufacture of the plasticized base structure or during a separate phase on a transfer support.

P:\WPDOCS\LMD\Fred Shilling\peifications\772750pcC.dc-12IO -2- When a continuous process is carried out, at the end of a line for producing the plasticized PVC base structure a uniform layer of a PVC plastiol composition is deposited on the surface, for example using a doctor blade, in an amount from 800 g/m2 and 1200 g/m2, 00 and said layer is dusted with silicon carbide particles or other particles having little r 5 sensitivity not only to plasticizers, solvents or other additives contained in the plasticizer, but also to the gelling, especially temperature, conditions.

O

C Particles are deposited in this way in an amount from 100 to 300 g/m2 and generally have a particle size between 200 [m and preferably 400 pm.

The complex thus covered with particles then passes through an oven in which the gelling operation is carried out at a temperature of 180-195°C for a time of 3 min 30 s to 4 min s, the complex on leaving the oven then being subjected to a slight embossing treatment by passing it between the rolls of a calender comprising a rubber roll and an unheated steel roll.

During its passage between the rolls of the calender, the complex is at a temperature of around 140 0 C, the steel roll being, by simple heat exchange, raised to a temperature of around 40 0

C.

The material thus produced exhibits good nonslip properties, both when dry and when in the wet state.

As an indication, such a material has a friction coefficient in the wet state of greater than or equal to 0.3, said coefficient being determined according to the BS 6677, part 1, 1986 standard.

However, it is difficult to maintain, because it has a high overall roughness in order to obtain the nonslip character. In fact, its roughness index Ra is between 5 and 10 pm and Rz (DIN) is between 20 and 40 gm. Moreover, it has a roughness in the regions between the particles, which roughness does not contribute to the nonslip function, but greatly P:\WPDOCS\LMD\Fred Schillingspmciflcatis\772975spc.dOC-1210O5 -3promotes fouling since, in these regions, the roughness index Ra varies from 1.5 gm to 3 gm and the index Rz (DIN) varies from 8 to 20 gm. This measurement is carried out according to the procedure 92 CT 03/1 (CTIP: Centre Technique International de l'hygiene, [International Hygiene Technical Center], Cleanness and maintenance of Cr 5 premises).

Summary of the invention An improved method has been found, and it is this which forms the subject of the present invention, which makes it possible to produce a novel type ofnonslip floor covering which not only is very durable and effective over time but also is easy to maintain without any risk of fouling.

According to the present invention there is provided a method of providing a surface covering to a base material or structure, said method including: depositing a transparent or translucent layer of a heat pregelled PVC plastisol on the upper face of the base material; covering the plastisol layer with a layer of thermosetting powder and subjecting the layers to a heat treatment to form a film; depositing particles of an abrasive material, such as silicon carbide or the like, onto the film while the film is still in a liquid form; passing the resultant covering through a hot-air oven to cause the plastisol to completely gel, the film to crosslink and the particles to be entrapped in the film; and embossing the covering.

P:\WPDOCS\1MD\Fred Schilling;spedfications\7729750spe.doc-2/01/0 -4- Preferably the process of the invention is carried out as a continuous process where

(N

a length of base material is formed with a covering as described and wound up as a roll after the covering has been embossed.

00 According to a preferred process of the present invention there is provided a N_ plasticized PVC base structure to which a surface covering is applied. That base O structure maybe optionally reinforced with a textile reinforcement such as cellulose N and nonwoven glass, and which is further optionally provided with an additional backing, such as an additional foam backing.

According to a preferred embodiment of the invention, the heat treatment allowing the thermosetting powder to be converted into a liquid film is carried out by combining the action of an infrared rail with passage through a hot-air tunnel.

The infrared radiation raises the material to its melting point, that is to say to a temperature generally between 100 0 C and 200'C, achieved over a time from one to thirty seconds. The action of the hot air allows the film to be smoothed out, the temperature of the air being between 80 and 120'C and the duration of the treatment being between thirty seconds and one minute.

By means of such a process, a coating is therefore obtained which comprises a pressed, extruded or calendered PVC base structure, which may be reinforced by a reinforcement, such as a glass-fibre mesh/nonwoven complex, and covered on its reverse face with a backing such as a foam layer, and the visible face of which includes a layer of surface coating in which particles giving the assembly nonslip properties are encrusted.

This covering is characterized in that the surface layer combined with the base structure is formed by a two-layer complex comprising a thermoplastic layer, preferably based on plasticized PVC like the base structure, coated with a film based on a thermosetting polymer, more particularly polyester, the particles giving the nonslip properties being encrusted in the thickness of said surface layer but still being visible.

P:\WPDOCS\LMD\Fred Schillingspmificatios\7729750spm 1/10 The PVC-based thermoplastic surface layer is obtained from a PVC plastisol composition (PVC resin, plasticizer and conventional stabilizers and rheological additives), this surface layer being colored or transparent and preferably between 0.2 and 0.8 mm in 35 in thickness.

The external layer combined with this PVC-based layer is itself produced from a thermosetting powder composition exhibiting crosslinking (curing) characteristics in a N short time, preferably between one and seven minutes at most, at a temperature between 180° and 210 0

C.

The formulation of this powder is such that it allows adhesion to the plasticized polymer (PVC) without impairing the flexibility qualities, the curing agent also not being aggressive toward PVC.

Such a powder may be obtained from a composition comprising: a hydroxylated polyester resin, a carboxylated polyester resin, a polyurethane resin, a polyester/epoxy hybrid resin, etc.; a crosslinking agent of the glycidyl ester type, a crosslinking agent of the hydroxyalkyl amide type or a crosslinking agent of the blocked or dimerized isocyanate type.

Compared with the prior nonslip floor coverings, a covering according to the invention may have a high overall roughness, the index Ra being between 4 and 7 Im and the index Rz (DIN) being between 15 and 40 jim.

Such a material may not only have the characteristic of being nonslip but also has improved surface properties such as resistance to fouling, scratching, wear, abrasion and scuffing.

P:\WPDOCS\LMD\Frd Schilling\spmirictions\7729750sp.d 12/ -6- Brief description of the drawings The invention and the advantages that it affords will however be more clearly understood from the description of embodiments which follow and as illustrated by the appended drawings in which: Figure 1 is a schematic view of a line for producing a floor covering according to the invention; and Figure 2 is a schematic view, in perspective, illustrating the general structure of a nonslip floor covering as produced by the line section shown in Figure 1.

Best modes Referring to the appended figures, a PVC base structure is conventionally produced, in a first operating phase, by pressing or calendering.

Such a base structure may be reinforced with a layer of textile material and may include, on its reverse side, a backing such as a foam layer (la).

According to the invention, the surface covering of the base complex thus formed is produced by depositing, on the upper face of this support a uniform layer of a plastisol based on a thermoplastic, especially PVC.

This plastisol is deposited in a conventional manner by making the support pass over a roll associated with a doctor blade The plastisol layer which may be coloured or transparent, has a thickness of between 0.2 and 1 mm.

The assembly is subjected continuously to a pre-gelling heat treatment raising the material to a temperature between 120 and 130'C over 30 to 60 seconds by passing it through a hotair or infrared oven P:\WPDOCS\LMD\Frcd SciILig\specifications\7729750spC.dC-12/1fO5 -6a- Onto this plastisol layer which is therefore solidified by the pre-gelling, is then Ni deposited a thermosetting powder composition 00 17- 7 The layer is deposited in this way by electrostatic coating by means of a powder coating system which may be a hopper combined with an electrostatic charging unit or a conventional electrostatic spray gun system suitable for flat powder coating. This layer is deposited in an amount from 20 to 200 g/m 2 preferably between 40 and 100 g/m 2 After the heat treatment preferably by means of a unit combining the action of an infrared rail with the action of hot air, the powder is converted into a continuous liquid film. The infrared rail raises the material to its melting point, between 110 and 200 0

C,

over a time possibly varying from one to thirty seconds. The molten material is then subjected to the action of hot air in a tunnel oven, the temperature of which is between 80 and 1200C, for a time of thirty seconds to one minute.

A liquid film with a thickness between 15 and 150 pm and preferably between 30 and 80 pm is thus produced, and continuously deposited on its surface are particles intended to give the material its nonslip properties.

Such particles preferably consist of silicon carbide and have a particle size from 400 to 800 pm.

The complex thus formed is then subjected to a heat treatment inside a hot-air oven causing the thermoplastic layer to gel completely, the thermosetting layer to. crosslink and the particles to be entrapped in this thermosetting layer The temperature inside the oven is set between 180 0

C

and 210'C, the treatment time being between one and seven minutes.

8 The complex thus formed is then taken up, for example in the form of a reel.

Figure 2 shows schematically, in cross section, the general structure of such a floor covering, therefore comprising a base support covered with a two-layer structure which may or may not be transparent and consisting, on the one hand, of a thermoplastic, preferably plasticized PVC, layer combined with a film based on a thermosetting, especially polyester, material, the particles (10) conferring nonslip properties on the structure being embedded in said surface layer It should be noted that, in such a material, the various layers of which it is composed are in the form of juxtaposed strata, firmly linked together but with no interpenetration, thus preventing any impairment in the properties of each of the individual layers.

Example The surface covering of a base structure produced beforehand, comprising a foam backing (la) combined on the reverse side with a PVC sheet (lb) is produced by means of a plant as described above.

Such a support has a thickness of 1.5 pm.

Deposited on the surface of this support by means of the doctor blade is a 625 g/m 2 layer of a plastisol possessing a viscosity of 200 centipoise (cps) and having the following composition: polyvinyl chloride (100 parts); plasticizer of the dioctyl phthalate type; stabilizer of the thiobutyltin type; diluent.

9 A layer having a thickness of 0.5 mm is thus formed on the surface of the support The assembly is then subjected to a heat treatment by passing it under an infrared rail raising the material to a temperature of 110°C and causing the layer based on the PVC composition, to pre-gel and therefore cure.

A thermosetting powder, consisting of a polyester-based composition, is conventionally deposited by electrostatic means in an amount of 60 g/m 2 downstream of the infrared rail The complex is then subjected to a second heat treatment combining the action of an infrared rail and of hot air. The infrared rail raises the powder to a temperature of 1200C over a time of ten seconds, causing it- to melt and a liquid film to be formed, which is subjected to the action of hot air at 95CC for a time of forty seconds, causing said film with a thickness of around 50 pm, to be smoothed out.

Immediately after the heat treatment, silicon carbide particles having a particle size of 600 pm are deposited on the surface of the still liquid film the amount deposited being 200 g/m 2 The particles (10) are distributed randomly and are encrusted in the surface layer The coating thus formed then passes through a hot oven at a temperature of 2100C, the treatment time being 3 minutes.

At the exit of the plant, a floor covering as illustrated in Figure 2, with a total thickness of 2 mm 0.1 mm, is obtained.

10 Such a floor covering exhibits very good nonslip properties, the overall roughness Ra being 4.8 pm with a roughness index Rz (DIN) of 30 pm and the maximum Ry value being 100 pm over the length evaluated.

Moreover, it has been found that, compared with the prior coverings, it possesses improved surface properties, especially as regards resistance to fouling, scratching and abrasion, these characteristics being obtained not only by the presence of the thermosetting-polymer-based surface film but also by the fact that, in the regions between the particles, the roughness is virtually zero since the Rz (DIN) index in these regions is about 0.8 pm and the Ra index is about 0.16 pm.

The specifications relating to tough floor coverings of the homogeneous or heterogeneous polyvinyl-chloridebased floor covering type are prescribed in European Standard NF EN 649 of December 1996.

The normative reference EN 425 relating to the action of a chair with castors makes it possible to demonstrate an improvement in the properties of the surface-treated product according to the invention compared with a conventional untreated product, that is to say a covering whose surface layer consists only of a thermoplastic layer.

Likewise, measurement of the slip of the floor coverings with the FSC 2000 instrument (Test Method TX- S018) shows that the specimen according to the invention exhibits a slip resistance (Fy/Fz) of 0.6 whereas a conventional product has a value of 0.37.

In addition, a test simulating wear of the high commercial type (TX-16/99 placement) shows the excellent behavior of the product according to the invention possessing a themoset surface layer.

11 Finally, a measurement of the emission of volatile organic compounds (VOCs) according to the PrEN13419-2 standard, carried out according to the emission test method (FLEC cell), gives the following results: Tvoc (Ag/m 3 tol. Tvoc ()g/m 3 tol.

eq at 3 days) eq at 28 days) Conventional covering 530 99 Covering according to 0 the invention

Claims (7)

1. A method for producing a non-slip floor covering formed on a base material or 00oO structure, said method including; depositing a transparent or translucent layer of a heat pregelled PVC 0 plastisol on the upper face of the base material; covering the plastisol layer with a layer of thermosetting powder and subjecting the layers to a heat treatment to form a film; depositing particles of an abrasive material, such as silicon carbide or the like, onto the film while the film is still in a liquid form; passing the resultant covering through a hot-air oven to cause the plastisol to completely gel, the film to crosslink and the particles to be entrapped in the film; and embossing the covering.

2. The method of claim 1, when carried out as a continuous process applied to a length of base material which is wound up after the embossing.

3. The method of claim 1 or 2, characterized in that the heat treatment to form the film is obtained by the combination of infrared radiation followed by passage through a hot-air tunnel.

4. A non-slip floor covering when made by the method of anyone of the preceding claims.

P:\WPDOCS\LMD\Fred Schillinspwficatims\7729750spcm1/10 -13- The floor covering of claim 4, characterized in that the thermoplastic surface layer is based on plasticized PVC, which may or may not be transparent, and has a thickness of between 0.2 and 1 mm, and the surface film made of thermosetting polymer is based on 00 polyester and has a thickness of between 15 and 150 utm, preferably between 30 and 80 pm N,

6. A method for producing a non-slip floor covering substantially as hereinbefore Sdescribed with reference to the accompanying drawings.

7. A non-slip floor covering made by the method of claim 6.