NO129727B - - Google Patents

Description

The present invention relates to an antistatic carpet construction, and more particularly a carpet construction which has a fibrous layer, an antistatic, conductive coating and a base of polymer material.

Conventional carpet constructions are able to develop

and transfer significant charges static electricity. These charges of static electricity are created when people in contact with the dielectric fibrous layer of the carpet move over this fibrous layer. The charge itself is created by the movement of dielectric shoe parts, which are in contact with the dielectric fibrous layer. These charges are then transferred to the wearer of the shoe. When the person wearing the shoe comes into contact at a later stage

otherwise with earth, the accumulated charge is discharged through the part of the person's body that is in contact with the earthed connection. This discharge can result in severe discomfort for the person.

The above-mentioned problem can be eliminated if the charges with

static electricity can spread throughout the entire carpet construction,

and later lost to the air.

Several antistatic compositions and an antistatic carpet construction have previously been described. In this antistatic carpet construction, which is referred to in the U.S. patent no. 2 302 003, accumulated charges are spread via several conductive fibers which are placed throughout the fibrous layer. In contrast, the charges of static electricity, which occur in the carpet construction according to the present invention, dissipate quickly and completely without the need for special conductive fibers. The carpet construction according to the invention diverts the charges with static electricity via a decisive conductive layer. The continuous conductive layer in the present carpet construction must be such that it is able to conduct and spread static electricity charges. However, the aforementioned antistatic layer must not have such a thickness that this interferes with the carpet's aesthetic properties.

According to the present invention, an antistatic carpet construction is provided and this is characterized by the fact that it essentially consists of a fibrous textile layer, a layer with an antistatic coating composition which essentially consists of a mixture of an antistatic agent, an ionic or non-ionic moisture -preservative, and, when this humectant is non-ionic, an electrolyte, which coating composition is on

one side of the fibrous layer, as well as a substrate of polymer material which covers the antistatic layer, the antistatic layer being placed between the fibrous layer and the substrate of polymer material.

Most of the previously known antistatic compositions cannot be combined with polymer substrates. Because of this incompatibility, carpets treated with these previously known antistatic compositions could not use most polymer underlays, and especially the commonly used natural latex underlay. In contrast to this, the antistatic coating in the composition used in the carpet construction according to the invention is compatible with natural latex bases and most other polymer coating compounds. Therefore, the antistatic carpet construction according to the invention can use a latex base.

The present antistatic carpet construction is illustrated in fig. 1. The carpet structure 2 has a conventional fibrous layer 4, which can be woven, shaggy, stretched, shaggy or have another construction that is common in carpets. This fibrous layer may be composed of any of the common textile fibers or mixtures thereof used in carpet manufacture, such as wool, polyamides (e.g. Nylon 66 and Nylon 6), cotton, polyolefins (especially polypropylene), acrylic fibers, modacrylic fibers, polyesters. The fibrous layer 4 is interwoven, tied through, or otherwise attached to a substrate 5, which is usually a woven fabric of cotton or jute, although other fibers and construction types can be used as substrate material. This basic rug construction can be any rug make, such as the well-known tufted rugs, Brusse rugs, Wilton rugs, Axminster rugs, Chenille rugs, velvet rugs, and knit rugs. According to the present invention, the underside of the fibrous layer or pole layer 4 and the main substrate 5 to which the fiber-forming pole is attached or through which it is connected, etc. is coated with an antistatic coating 6 which provides a uniform layer and covers and touches the substrate and the ends of the fibers that form the pole in contact with this substrate. The quantity of the material applied as an antistatic coating should be sufficient to significantly penetrate the substrate and the part of the fibers that are in contact with it, but should preferably not be applied in such a way or in such a quantity that it penetrates in the front of the fibrous layer 4, because this destroys the aesthetic properties of the fibrous layer. Normally from 0.37 to 444 g per m 2 and preferably from 18.5 to 111 g per m 2 of the antistatic coating is applied.

The antistatic coating composition used in the antistatic coating layer 6 essentially consists of a mixture of one textile antistatic agent and the humectant in amounts of from 4 to 8 parts by weight antistatic agent and 10 to 50 parts by weight humectant. Preferably from 0.1 to 1 part by weight of a non-ionic or cationic wetting agent is also introduced to aid the penetration of the antistatic composition into the textile substrate. It is desirable to add the wetting agent in controlled quantities (determined from initial trials) in order to thereby control the degree of penetration of the composition into the textile substrate so that the antistatic coating composition penetrates into the carpet's substrate and moistens the bottom of the pile fabric, but so that it does not go as far as the outer tips of the pole tissue. If the humectant used is non-ionic or is only weakly ionic, i.e. has a relatively low dissociation constant, an electrolyte is used as mentioned in the coating composition and preferably in an amount of 0.1-1 part by weight. The antistatic coating 6 is preferably applied in the form of an aqueous solution or dispersion, although other solvents or liquid dispersing media can be used if desired and in the case of aqueous solutions or dispersions, volatile non-soluble solvents, such as lower aliphatic alcohols with from 1 to 5 carbon atoms, acetone and the like, are included to facilitate drying of the antistatic layer after its application.

After the antistatic coating 6 has been placed on the underside of the carpet, a bottom layer 8 of polymer material is applied to the carpet and forms an essential element in the carpet construction according to the invention. This polymeric base layer is preferably placed in the form of an aqueous dispersion (latex) and is preferably a known mixed natural rubber latex or mixed carboxylated butadiene-styrene rubber latex, which is usually used as a latex base in carpets, although other polymer coatings, such such as polystyrene, vinylidene chloride, polyacrylates, butadiene-styrene rubbers and the like can be used. As examples of known natural mixed rubber latexes, which are commercially available, can be mentioned: "Lotol GX-31d0" and "Burkote R 1732", compound carboxylated-styrene-butadiene-rubber latexes such as "Lotol GX-1314" , or composite neoprene latexes such as "Lotol-GX-1076" and "Burkote R 2285".

Although the actual reasons for the antistatic properties of the carpet construction according to the invention are not fully understood, it appears that the polymer coating 8 serves to keep the antistatic coating layer 6 in place. Charges of static electricity that accumulate in the pole material 4 are spread over the entire carpet surface by the antistatic layer or layer 6 and are later diverted to the ground or to the atmosphere. To assist the conduction of these leads to ground, the polymer coating b may comprise a material such as carbon black or any other agent that will lower the dielectric properties of the polymer layer.

Several preferred compositions for the antistatic coating layer 6 in the carpet construction according to the invention are described in British patent no. 1 182 191. Particular preference is given to the antistatic compositions in which potassium formate is used as a humectant, because it has been found that potassium formate is not only particularly effective as a moisture-preserving agent in such coating compositions, but compositions containing this compound are also compatible with the latex base layers that are normally used in carpets, and overcome in particular early coagulation or gel formation of the latex base layer which is based on naturally composed rubber , and thus does not prevent a good addition of the latex coating to the back of the carpet. On the other hand, the antistatic coatings containing calcium chloride are incompatible with certain known latex coatings which have been used as carpet underlays in that they cause premature coagulation or gelling of the latex with resultant poor adhesion of the latex to the carpet backing. so, in the case of loosely woven or knotted carpets, that the latex does not act satisfactorily to hold the individual threads in place.

Although the antistatic layers based on the antistatic compositions of the above patent are particularly preferred,

it should be understood that one can use any antistatic layer based on any known antistatic material for textiles, which will dissipate charges of static electricity. Such agents are normally nitrogen-containing or carboxyl-containing organic antistatic agents and the following compounds should be mentioned as examples of these:

"Burkester R 1499" - Lauric acid polyethylene glycol ester Amine oxides or quaternary ammonium salts of vinylpyrrolidone - dimethylamino-ethyl methacrylate copolymers Vinyl-pyrrolidone-acrylamine copolymers - such as a copolymer of 75% vinyl 1-pyrrolidone and 25% acrylamide "Zelec DP" - lauryl -alcohol phosphate "Catanac SN" - stearylamidopropyl dimethyl-g-hydroxyethyl-1-ammonium nitrate "Ethoquad C/12" - polyoxyethylated quaternary ammonium salt Posphonamide sulphonate of an alcohol ethoxylate, i.e. a product of the formula:

where R denotes an unbranched or branched alkyl radical with 6-22 carbon atoms, or an alkylaryl radical with 4-18 carbon atoms, and n is an integer from 1 to 100.

Partial esters of the copolymer of vinyl methyl ether and maleic anhydride with nonionic surfactants, described in French Patent No. 1,360,209.

Phosphate esters of the type described in US patent no.

3 004 056 and no. 3 004 057 and in Belgian patent no. 641 097. Triesters of phosphoric acid and ethoxylated aliphatic alcohols such as the phosphate triester of lauryl alcohol condensed with 4 moles of ethylene oxide or of dodecyl alcohol condensed with approx.

2 moles of ethylene oxide.

"Polyglycol 4000"

Sucrose octa-acetate

Polyethoxyamides of stearic and oleic acid Methyldiethanolamine ethoxylate

Ethoxylated 2,3,7,9-tetramethyl-5-decyne-4,7-diol Polyoxyethylene mono-oleate

Lauryl trimethyl ammonium chloride

Undecylimidazolone

Lauryldimethylbenzy1 ammonium chloride

Polyoxyethyl-stearyl ammonium chloride

Olein monoisopropanolamide

Vinyl acetate/styrene/acrylic acid polymers

Ethoxylated diamines

Amine oxides with lanee chains

Hydroxybutyramides

Quaternized polymers of vinylpyridine

Quaternized copolymers of vinylpyridine and vinylpyrrolidone

Particularly preferred are antistatic layers based on alkylated tertiary amines represented by the following general formula:

in which R represents an aliphatic hydrocarbon radical with from 8 to 22 carbon atoms, each R' represents hydrogen or methyl and n represents an integer of at least 1, preferably from 1 to 30, although higher alkylated derivatives, i.e. the products obtained by condensation of a molar amount of a primary aliphatic (saturated or unsaturated) amine with up to 50 molar amounts of an alkylene oxide, usually ethylene oxide, can be used if desired. Such alkylated amines are well known in the art and are prepared by condensing the primary saturated or unsaturated aliphatic amine with from 8 to 22 car-

bon atoms, with an alkylene oxide, usually ethylene oxide, although propylene oxide and butylene oxide may be used if desired, until glycol groups of the desired chain length are provided.

Various deliquescent salts of metals from groups I and II in the periodic table, especially salts of the alkali metals and the alkaline earth metals, can be used as a moisture-preserving agent in the composition according to the invention. Particular deliquescent salts preferred as humectants include the alkali metal salts of lower aliphatic carboxylic acids, such as sodium formate, potassium formate, lithium formate, cesium formate, sodium and potassium acetate, potassium butyrate, and mineral acid salts such as calcium chloride. You can also use such organic moisture control agents as glycerol, urea, ethylene glycol, sorbitol, ethoxylated sorbitol, lauric acid esters and mixtures thereof.

When a deliquescent salt is used as a moisture preservative

end agent, it can also act as an electrolyte. However, when glycerin or other nonionic humectants are used, they should be combined with an electrolyte. Also in the case of such deliquescent salts as sodium and potassium formate, which have a relatively low dissociation constant, it is best to incorporate a small amount of a salt of a strong base and strong acid with a high dissociation constant, such as sodium chloride, potassium chloride or calcium chloride. Salts which are not sufficiently deliquescent such as sodium chloride, sodium sulphate, potassium nitrate, so that they do not. appears fully satisfactory as both humectant and electrolyte, can be used in combination with a non-ionic humectant, such as glycerin or urea or in combination with an even more deliquescent salt, such as potassium formate or calcium chloride. The moisture-preserving agent and the electrolyte can thus in the construction according to the present invention either be a single compound or a mixture of compounds.

If desired, a further background material, such as a jute layer with the designation 10 in the drawing, can be placed over the latex coating, but this is not an essential element in the carpet construction according to the invention.

The details of the present invention will emerge better from the following special examples where the parts are given as parts by weight.

Examples 1 to 14

In these examples, the antistatic composition was made by adding the base and the organic acid to water to form the humectant in situ. The alkoxylated amine used was stearylamine, which had been ethoxylated with 20 moles of ethylene oxide per mole of amine. The wetting agent was tridecyl alcohol which had been ethoxylated with 6 moles of ethylene oxide per mole of alcohol. The amounts of material used in each example are given in Table I.

In all cases, the antistatic coating was applied to the back of a carpet with dot-shaped threads provided with a loosely woven jute backing, and the types of fibers used in the dot-shaped pile material are given in Table I as well as the amount of antistatic composition applied to the back. off the carpet. After applying the antistatic coating, the carpet was dried to remove excess moisture. A latex coating was then placed over the antistatic coating in such a way that it did not encapsulate the antistatic coating.

The test method used in these examples was "the Walking Foot Scuff Test". This test method is as follows: A carpet sample with a length of 2.7 ni and a width of 0.6 to 0.9 m is placed on the floor. At one end of the carpet, an electrostatic voltmeter is placed on a table. Starting from the end of the carpet where the voltmeter is placed, the experimenter, wearing shoes with leather soles and heels, constantly dragging his feet, walks to the opposite end of the carpet, turns while remaining on the carpet, and turns back to the voltmeter end of the carpet where the experimenter immediately touches the voltmeter's follower with his hand. The electric charge collected in the experimenter is transferred to and recorded on the voltmeter. In all the examples, the experiment was carried out at 25°C + 1°C and at a constant relative humidity of from 35 to 40%.

Examples 15 to 31

In these examples, the treated samples were frayed carpet constructions of nylon and wool. In all cases, the antistatic coating was placed at the base of the carpet fibers and on the jute base and dried. A latex coating was then placed over the antistatic coating in such a way that it did not encapsulate the antistatic coating.

In these examples, the humectant was formed in situ by reaction between a basic component and an acidic component. The amine and wetting agent were the same as described in Examples 1 to 12.

The test method used in the present examples was "the Stationary Poot Scuff Test". This method is as follows: The carpet to be tested is placed on the floor (at least 44 cm x 44 cm) and the experimenter, wearing shoes with leather uppers and soles, stands on the carpet with one foot at rest. While holding a voltmeter follower in one hand, the experimenter rubs his other foot rapidly back and forth on the carpet, a maximum of 15 times or until the meter reaches equilibrium. Any resulting charge is transferred through the person and registered on the voltmeter. This experiment was carried out at 25°C + 1°C and at a constant relative humidity of from 35 to 40%.

The composition of the antistatic coating, as well as the test results, and other information regarding these examples, are given in Table II.

Examples 32 to 46

In these examples, the treated samples were carpet constructions of nylon and wool with a dotty appearance. In all cases, the antistatic coating was placed at the base of the carpet fibers and on the jute base and dried to remove excess moisture. In these examples, the wetting agent used was the same as in examples 1 to 15. A latex coating was placed in such a way that it did not encapsulate the antistatic coating.

In the examples, the humectant was not formed in situ, but was added directly to the antistatic composition. In Examples 38-41, the calcium chloride acted both as a humidity control agent and as an electrolyte. The test method used in Examples 32, 33, 35, 36, 38, 39, 41--44 was "the Stationary Foot Scuff Test", as described above in connection with Examples 15 to 31. "The Walking Foot Scuff Test" was used in Examples 34, 37 and 40 in the same manner as discussed in Examples 1 to 15. These tests were carried out at 25°C +1°C and at a constant relative humidity of from 35 to 40%.

The composition of the antistatic coating, as well as the test results and other information in connection with the tests are given in Table III.

Examples 47 to 75

In these examples, the treated samples were conventional woven and nonwoven fabrics. In all cases, the antistatic coating was placed on the textile material and dried to remove excess moisture. The amine used was the same as in examples 1 to 15. In the present examples, no wetting agent was used, in order to prevent the antistatic coating from completely penetrating the textile material.

In these examples, the humectant was formed in situ by reaction between a basic component and an acidic component as in examples 1 to 15. The procedure in these examples was as follows: The samples were cut and coated with the antistatic coating. In these examples, the coating weight was based on the weight of the textile material present. A polymeric background material was then applied to the fabric and dried at a temperature of from 93° to 163°C for approx. 10 to 30 minutes. The dried tissue was then conditioned for at least 6 hours at a temperature of 21° + 3°C and at a relative humidity of 35 to 40%. The coated material was then tested on an "Atlab tester", made by Atlas Chemical Co. The test method essentially consists of devices for controlled rubbing of a substance over a pair of rods ("Teflon") for the development of static electricity and over a stainless steel rod, which transfers the friction-generated charge to an electrostatic voltmeter for measurement. This experiment was conducted at 25°C + 1°C and at a constant relative humidity of 35 to 40 J5.

The composition of the antistatic coating, as well as the trial results and other relevant information are given in Table IV.

Examples 76 to 108

In these examples, the treated samples were conventional woven and nonwoven fabrics of the fiber type shown in Table V. In all cases, the antistatic coating was placed on the back of the textile sample and dried to remove excess moisture. A polymeric background material was then applied to the tissue and cured at a temperature of from 93° to 163°C for 10 to 30 minutes. The coated material was then tested in an "Atlab tester" in the manner described in Examples 7^-75. In the present examples, the humectant was not formed in situ, but was added directly to the antistatic composition.

The composition of the antistatic coating as well as test results and other data relating to these examples are given in Table V.

Claims (3)

1. Antistatic carpet construction, characterized in that it essentially consists of a fibrous textile layer, a layer of antistatic coating composition consisting essentially of a mixture of an antistatic agent, an ionic or nonionic humectant, and, when said humectant is nonionic, an electrolyte, which coating composition is on one side of the fibrous layer, as well as a substrate of polymer material which covers the antistatic layer, the antistatic layer being placed between the fibrous layer and the substrate of polymer material. 2. Antistatic carpet construction according to claim 1, characterized in that the fibrous textile is of the pole type with the fibrous pole fixed in and projecting on one side of a woven textile construction, and in that the antistatic coating composition is located on the woven side of said pole. 3. Antistatic carpet construction according to claim 2, characterized in that the fibrous textile is a frayed carpet construction with pile fibers connected through a woven base. H. Antistatic textile product according to claims 1-3" characterized in that the antistatic agent is an alkylated tertiary amine.