CH630427A5 - Method for making a flexible and resilient ground covering - Google Patents

Description

The subject of the invention is a process for manufacturing a coating by successive and alternating applications of a polyurethane binder and solid particles of elastic or plastic nature. These coatings are applicable, in particular, to the construction of tennis courts, sports fields, gymnasiums and playgrounds.

It is known to produce floor coverings by applying, on a support, several layers of a paint consisting of a binder, generally of vinyl or acrylic nature, and a mineral filler, such as fine sand. Due to their rigidity, these coatings tend to crack and cause excessive fatigue in users. They also have low wear resistance, as well as poor surface properties, these coatings often being too rough in dry weather and too slippery in wet weather.

In order to obtain better quality coatings, it has previously been proposed to use elastic binders, such as two-component polyurethane binders, containing rubber granules in suspension. The latter having the disadvantage of leading to very viscous mixtures, it is necessary, in practice, to use fairly large granules, of dimensions generally varying from 2 to 5 mm, the thickening effect of which is less than that of the more granules. small, and limit their proportion to 30% by weight in the mixture. Due to the dimensions of the granules used, these coatings can only be applied in relatively thick layers; containing moreover relatively few granules, these coatings know only a limited development, because they are expensive and inconvenient to apply.

It has now been found that it is possible to produce economically and conveniently, using a polyurethane binder and elastic or plastic particles, thin coatings having good mechanical and use properties.

The subject of the invention is therefore a process as defined by claim 1. In a particular mode of application of the process according to the invention, it is possible for example: i) to apply to a support a polyurethane binder whose viscosity, between —10 and 40 ° C, is between 5 and 30 Po in quantities between 200 and 1000 g / m2, ii) distribute on the binder solid particles in sufficient quantity to cover the binder layer, iii) eliminate, if necessary and after at least partial crosslinking of the binder, the particles not retained by the binder, then iv) repeat this sequence of operations one or more times, until the coating has the desired thickness.

The polyurethane binder may comprise, as an essential constituent, a polyurethane prepolymer obtained by a preliminary reaction between organic polyisocyanates and hydroxylated compounds, these compounds being used in proportions such as the isocyanate index, which is equal to the ratio of the number of isocyanate groups of the polyisocyanates to that of the mobile hydrogen atoms of the hydroxylated compounds, either greater than 1 and preferably between 1.5 and 10. The crosslinking of this polyurethane binder can be obtained by the action of air humidity, after application of the binder, or by a more or less complete reaction of the binder with hydroxylated compounds mixed with the binder at the time of application; the quantity of hydroxylated compounds used is then calculated in such a way that the isocyanate index of the mixture, which is equal to the ratio of the number of isocyanate groups of the prepolymer to that of the mobile hydrogen atoms of the hydroxylated compounds, does not drop not below a value approximately equal to unity; in practice, this value is between 0.9 and 10.

The polyurethane binder can also be obtained by mixing, at the time of application, organic polyisocyanates and hydroxylated compounds, these compounds being used in proportions such as the isocyanate index, which is equal to the ratio of the number isocyanate groups of the polyisocyanates to that of the mobile hydrogen atoms of the hydroxylated compounds, ie between 0.9 and 10.

The organic polyisocyanates used in the preparation of the binders of the process according to the invention are preferably chosen from aromatic polyisocyanates such as tolylenediiso-cyanate commonly called TDI and used commercially in the form of a mixture of isomers 2-4 and 2- 6, the most frequent mixtures containing 80 or 65% by weight of the 2-4 isomer, diphenylmethane-4-4'-diisocyanate, commonly called MDI, and polyphenyl / polymethylene / polyisocyanates, sometimes designated by the brand Papi . TDI and MDI can also be used in raw form; the crude TDI is for example constituted by the product of the reaction of phosgene on crude tolylenediamine containing various isomers and condensed amines, while the crude MDI results for example from the condensation of phosgene on the unpurified product of the reaction between l aniline and formaldehyde.

The hydroxylated compounds used in the preparation of the described binders preferably consist of polyols, of the polyether / polyol type or of the polyester / polyol type, having, on average, from 2 to 6 hydroxyl groups per molecule and an equivalent weight included. between 500 and 5000. The equivalent weight is equal to the quotient of the average molecular weight by the average number of

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hydroxyl functions existing per molecule. Polyethers / polyols. are generally prepared by polyaddition of propylene oxide and, optionally, ethylene oxide, on a compound having 2 to 6 atoms of mobile hydrogen, such as polyalcohols, polyamines or amino alcohols. The polyesters / polyols are generally obtained by esterification of polyacids, such as adipic acid or sebacic acid, and / or of polyacid anhydrides, such as maleic anhydride or phthalic anhydride, with an excess of polyalcohols such as ethylene glycol, polyethylene glycols, propylene glycol, polypropylene glycols, glycerol or sorbitol.

The hydroxylated compounds may contain, in addition to the polyols mentioned above, compounds comprising only one mobile hydrogen atom per molecule, preferably consisting of compounds having a molecular weight of between 200 and 6000 and comprising a d atom. mobile hydrogen included in a hydroxyl group or in a secondary amine group.

These compounds can, for example, be chosen from fatty alcohols or fatty secondary amines, or result from the polyaddition of alkylene oxides such as propylene oxide and, optionally, ethylene oxide, over alcohols or secondary amines, such as ethanol or diethylamine. In this case, the polyols and the compounds having only one mobile hydrogen atom are, for example, used, in the preparation of the described binders, in proportions such as the ratio between the number of mobile hydrogen atoms polyols and that of the mobile hydrogen atoms of the compounds having only one mobile hydrogen atom is between 1 and 20 and preferably between 2 and 12.

The binders described can also contain fillers, in particular fine powder chalk or ground kaolin, as well as pigments, such as red iron oxide pigments. In order to obtain binders whose crosslinking time is between 1 and 24 h, and preferably between 3 and 12 h, it is possible to introduce catalysts for crosslinking isocyanate groups or for forming polyurethane groups, in particular organic metal compounds, such as organic tin compounds, or amines, particularly tertiary amines. The binders can also contain up to 20% by weight of plasticizers or up to 50% by weight of solvents such as aromatic petroleum oils, esters such as dioctylphthalate or chlorinated paraffins; the addition of plasticizers or solvents makes it possible, if necessary, to adjust the viscosity of the binders to the desired value.

The solid particles of elastic or plastic nature may, depending on the properties sought for the coating, be made up of various materials such as waste rubber or plastics, sawdust or cork; if necessary, these various materials can be used successively or as a mixture. The particle size of these particles is, for example, chosen so that at least 90% by weight of the particles pass through sieves of 1.5 mm mesh opening. The apparent specific weight of these particles is generally between 0.1 and 0.8 g / cm3, and even frequently between 0.3 and 0.6 g / cm3.

It has also been discovered that, unlike the prior practice, it is advantageous to use particles of irregular shape, having if possible crevices capable of retaining gas bubbles which contribute to the elasticity of the coating; such irregularly shaped particles can for example be obtained by shredding rubber in a mill with fluted cylinders.

The coatings produced by the process according to the invention can be applied to substrates of various kinds, such as cement concrete, asphalt or bituminous mixes. The application can be made directly, when the support is both dry and not very porous. It is preferable to apply a primer to the support beforehand; the latter is preferably a primer of the polyurethane type which can be prepared by diluting a polyurethane binder in a solvent. When the support is porous, it is useful to apply beforehand a sealer which can advantageously be constituted by a binder according to the invention whose viscosity has

been increased with thickening agents such as fine silicas, kaolin, hydrogenated castor oil or rubber powder.

The binder can be applied to the support at any temperature between -10 and 40 ° C and by any suitable means such as spraying, application with a roller or a brush. The solid particles of elastic or plastic nature are distributed over the binder layer, before it hardens, in a layer thick enough to completely cover the surface to be coated; this operation can be carried out by any known means, in particular by spraying or by spreading and leveling the layer by means of a doctor blade or a brush. When the binder layer is sufficiently crosslinked to fix the solid particles which have been at least partially immersed therein, the possible excess of solid particles is removed by sweeping or by suction. On the surface thus obtained, a new layer of binder is then applied, then again solid particles, and these operations are repeated until a coating of the desired thickness is obtained. The total thickness of these coatings is between 0.5 and 5 mm, and most often between 1 and 3 mm.

In order to increase the roughness of the coatings, it is advantageous to complete their production by applying solid particles. It is also possible to apply paint to the coverings; this paint is preferably of the polyurethane type and can be prepared like the binders described above.

Due to the flexibility and elasticity properties of the coatings obtained, the method of the invention is particularly applicable to the production of sports or playgrounds. These coatings also have good wear resistance and non-slip properties, in the dry or wet state. These characteristics are preserved over a wide temperature range, from -20 to 80 ° C, and they are also maintained in a durable manner. These coatings have the additional advantage of being very convenient to produce.

Example 1:

A prepolymer containing 3.5% by weight of free NCO groups is prepared, by reaction at 75 ° C, for 3 h, of 15 parts by weight of tolylene / diisocyanate 80/20 and 85 parts by weight of a triol of equivalent weight equal to 1000, obtained by polyaddition of propylene oxide on glycerol.

A binder is then prepared by mixing at 20 ° C. 80 parts of the above prepolymer, 10 parts by weight of red iron oxide, 10 parts by weight of ethyl glycol acetate and 0.3 part of dibutyltin dilaurate. The viscosity at 20 ° C of this binder is 16 Po.

The coating is carried out on a smooth and dry bituminous support. A first layer of binder is applied to the support with a roller, at a rate of 500 g / m2. Then spread on the binder layer, by means of a broom, a layer of polyurethane rubber granules, at a rate of 1000 g / m2. These granules, with a specific weight of 0.4 g / cm3, were obtained by shredding polyurethane rubber ingots in a mill with fluted cylinders, then sieving; their particle size is such that all of the granules pass through a sieve with a mesh opening of 1 mm. After 12 h, the granules not fixed by the binder are scanned; approximately 500 g of granules are thus recovered.

The same sequence of operations is repeated twice successively.

A coating with a thickness of 3 mm is obtained, the characteristics of which are as follows:

Density: 1 g / cm3

Appearance: solid, without cracks

Breaking strength (standard NF T 46 002): 28 daN / dm2

Elongation at break (standard NF T 46 002): 300%

Decrease in breaking strength after 3 weeks of UV irradiation at 60 ° C (standard NF T 30 049 Type E2): <10%

2.54 m high tennis ball bounce: 1.34 to 1.47 m

Wear resistance, measured using the Lhomargy usometer, with

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abrasive paper C 180, under a load of 1 kg and on 10 cm2 of surface: loss of 0.2 g after 1500 h

Slipperiness, measured with the RRL pendulum, on a scale from 0 to 150 dry coating: 90 wet coating: 72

Example 2:

A bonding primer is prepared by dissolving 50 parts by weight of the prepolymer of Example 1 in 50 parts by weight of ethyl acetate. A two-component polyurethane binder A and B is also prepared, with the following composition:

Component A (parts by weight):

Polyoxypropylene glycerol of equivalent weight = 1000: 30

Fine crushed chalk: 54.8

Kaolin crushed: 10

Molecular sieve 4 Â in powder: 2

Iron oxide red pigment: 3

Dibutyltin dilaurate: 0.2 Component B:

Prepolymer of Example 1.

The polyurethane binder is prepared at the time of application by mixing 100 parts of component A and 40 parts of component B (the isocyanate index is equal to 1.10). Its viscosity at 20 ° C is equal to 120 in. On a smooth, clean and dry cement concrete support, a layer of primer is applied. After drying, roller binder is applied at the rate of 800 g / m2, then a layer of poly (styrene butadiene) rubber granules is spread over the binder layer, at the rate of 1000 g. / m2.

These granules, with a specific weight of 0.45 g / cm3, are obtained by shredding rubber waste in a mill with fluted cylinders, then sieving; their particle size is such that all of the granules pass through a 1.5 mm sieve with an unraveled opening.

After 12 h, the unbound granules are scanned; approximately 400 g / m2 of granules are recovered. The coating and the granules are again applied, as described above.

A 2.5 mm thick coating is obtained, the characteristics of which are as follows:

Density: 1.1 g / cm3 Appearance: solid, without cracks

Resistance to rupture (standard NF T 46 002): 16 daN / dm2 Elongation at break (standard NF T 46002): 150% î s Decrease in resistance to rupture after 3 weeks of irradiation under UY at 60 ° C indoor (NF T 30 049 TypeE2 standard): <10%

2.54 m high tennis ball bounce: 1.43 to 1.47 m

20 Bounce of basketballs from a height of 1.80 m: 1.50 to 1.55 m, i.e. 100 to 105% compared to cement concrete

Resistance to cracking of the coating applied to cement concrete, measured using an EDF device:> 1.8 mm

Wear resistance, measured using the Lhomargy usometer, with 25 abrasive paper C180, under a load of 1 kg and on 10 cm2 of surface: loss of 0.6 g after 1500 h

Slipperiness, measured with the RRL pendulum, on a scale from 0 to 150: dry coating: 90 wet coating: 70.

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Claims (11)

630427 1. Method for manufacturing a flexible and elastic coating for floors, of thickness between 0.5 and 5 mm, by successive and alternating applications on a support of a polyurethane binder and solid particles of elastic or plastic nature in sufficient quantity to cover the binder layer, characterized in that the binder has a viscosity of between 1 and 200 Po at the application temperature, between -10 and 40 ° C., and that it is applied at the right rate from 100 to 2000 g / m2, and in that the solid particles are simply distributed over the surface of the binder without being compacted. 2. Method according to claim 1, characterized in that one applies a binder obtainable by reaction of organic polyisocyanates and hydroxylated compounds, in proportions such that the isocyanate index is greater than 1. 2 3. Method according to one of claims 1 or 2, characterized in that the binder is crosslinked by air humidity. 4. Method according to one of claims 1 or 2, characterized in that the binder is at least partially crosslinked by means of hydroxylated compounds, mixed with the binder at the time of application in proportions such as the isocyanate index of the mixture is between 0.9 and 10. 5. Method according to claim 1, characterized in that the binder is prepared, at the time of application, by mixing organic polyisocyanates and hydroxylated compounds, in proportions such that the isocyanate index is between 0.9 and 10. 6 hydroxyl groups per molecule and an equivalent weight between 500 and 5000. 6. Method according to claims 2,4 and 5, characterized in that the hydroxylated compounds consist of polyols, of the polyether / polyol or polyester / polyol type, having on average 2 to 7. Method according to claim 1, characterized in that the solid particles have a particle size such that at least 90% by weight of them pass through a sieve of 1.5 mm mesh opening. 8. Method according to one of claims 1 or 7, characterized in that the particles have an irregular shape and are provided with crevices. 9. Coatings produced by the process according to claim 1. 10. Application of the method according to claim 1 to the realization of sports or playgrounds. 11. Application according to claim 10 for the production of tennis courts, gymnasiums, running tracks or playgrounds.