GB2159184A - A conductive linoleum web - Google Patents

Abstract

The linoleum web contains an additive which improves the conductive and antistatic properties of the web and which comprises a compound having at least one heterocyclic ring with at least one nitrogen atom and at least another heteroatom. The additive causes an electric leakage resistance RA of <10<8> Ohm to be attained without impairing the optical, constructional and colouristic design possibilities and service properties as well as the ripening process of the linoleum.

Description

SPECIFICATION Improvements in or relating to a linoleum web The invention relates to a conductive, antistatically finished linoleum web.

The production of linoleum has been known for more than 100 years; with the exception of wet and outdoor spheres, its use extends over the whole variety of human living spaces.

According to Ullmann, Enzyklopådie der technischen Chemie, 4th edition, volume 12, pages 24-25, linoleum is a floor covering which can be produced in 30 m long, 2 m wide and 2-4 mm thick webs and consists of a coarse-mesh jute fabric, onto one side of which a covering compound, the so-called linoleum coating compound, is rolled under pressure. The linoleum coating compound is obtained by kneading together cork powder or wood flour, mineral fillers (e.g. finely ground chalk) and dyes with linoleum cement. The most important raw material for the production of linoleum cement, and thus for the production of linoleum, is linseed oil, which is transformed by the absorption of atmospheric oxygen into a solid, rubber-like elastic body, linoxyn. Other drying oils, such as soya bean oil, tall oil etc., also have these properties.However, because of their lesser drying properties, these oils can only be used for the linoleum production if they are blended with linseed oil. Linoxyn forms, together with natural resins, mostly colophonium, the linoleum binding agent proper, the so-called linoleum cement. The production of linoleum cement has been considerably simplified and rationalised during the past few years. Today, one works only according to the so-called rapid-oxidation method, wherein a strong air current is blown into linseed oil in a double-walled heatable and coolable horizontal oxidation tank, following the addition of a small quantity of siccative, at approximately 80 C along with vigorous stirring until a specific viscosity of the oil has been attained.Then approximately 20 % melted colophonium by weight are added and the temperature is increased to 130 - 150" C. The cement is thereafter extruded into a strand in a screw extruder, cut into approximately 40 m long pieces and cooled and stored in iron boxes until further processing.

For further linoleum production details reference is made to the literature quoted.

It is a disadvantage of the hitherto known linoleum that, because of its relatively high leakage values (RA > 1011 Ohm), it cannot be laid in rooms for whose functional purposes very specific leakage values of the floor covering are required. These rooms include, for example, operating and computer rooms. It is indeed possible to lower the leakage resistance of linoleum by the addition of conductive fillers, e.g. special carbon blacks and metal powder, but this causes the service properties and/or design latitudes of linoleum to be restricted. If carbon black is used, virtually no colour design possibilities exist and if metal powders are used, the colour design possibilities are considerably restricted; in addition, there come about changed characteristics in the mechanical behaviour as well as a heavy weight and a considerably reduced thermal insulation.

From the field of plastics engineering it is furthermore known that the electrostatic charge of plastics materials can be reduced by the addition of antistatic agents.

Compounds usable as antistatic agents are for example N,N-bis(hydroxyethyl)-alkylamine Oxethylated fat alcohols Oxethylated amines Oxethylated fatty acids Oxethylated alkyl phenols Sulphate esters of oxethylated alkyl phenols Phosphate esters of exethylated alkyl phenols Alkyl aryl sulphonates Alkyl sulphates Quaternary ammonium compounds and Alkyl pyridinium halides.

Because of the specific production technique dependent on raw materials, these antistatic agents cannot however be used for linoleum production, since it has turned out that such antistatic agents cause the ripening process (oxidation process following calendering) to be either completely prevented or at least delayed for an economically unacceptable period or that the effectiveness of the antistatic agents is reduced towards zero as the degree of oxidation of the linoleum increases.

Another possibility of increasing the conductivity is the use of agents which attract or regulate moisture, such as glycerin.However, in the case of linoleum, the necessary conductivities cannot be attained therewith, as the following measured values show.

Linoleum with 3.5 % glycerin: RA fresh: 7.5 x 109 Ohm.

RA ripened: 4.5 x 109 Ohm.

It is therefore the object of the invention to indicate a linoleum web which is usable as a floor covering and is characterised by an electric leakage resistance RA of < 108 Ohm while maintaining the optical, constructional and colouristic design possibilities and service properties, the ripening process of the linoleum not or only insignificantly being influenced.

According to the invention, the problem posed is solved by a linoleum web as characterised in the Claims.

Linoleum webs according to the invention can thus be produced in that there are added to the linoleum compound during its production compounds which have at least one heterocyclic ring with at least one nitrogen atom and with at least another heteroatom.

The fact that the addition of such heterocyclic compounds with at least two heteroatoms considerably increases the conductivity of the linoleum compound without impairing the ripening process and the other product characteristics and that the conductivity increase in maintained after the ripening process was not to be expected and has to be regarded as surprising.

Typically, the compounds usable according to the invention are compounds with at least one 5- or 6membered heterocyclic ring. There may be condensed to this ring possibly substituted rings, e.g. benzene rings. The second heteroatom may consist, for example, of an oxygen, sulphur or nitrogen atom.

Preferably, the second heteroatom consists of a nitrogen or oxygen atom. The rings or ring systems may be substituted, for example by straight-chain or branch-chain aliphatic residues or residues of an aliphatic nature, such as are typical of surface-active compounds, for example alkyl residues interrupted by oxygen atoms or -NH- groups.

The use of compounds with at least one aliphatic residue or a residue of an aliphatic nature with more than 6 C-atoms has proved to be particularly advantageous, causing the compounds to be given a surface-active or boundary-surface-active nature.

The use of compounds which have a quaternary nitrogen atom and are cation-active has furthermore proved to be particularly advantageous. Typical compounds usable according to the invention are, for example, compounds with a 5-membered heterocyclic ring, e.g. a thiazole, oxazole, isoxazole, pyrazole, imidazole, imidazoline, triazole, benzothiazole, benzoxazole, benzisoxazole, benzpyrazole, benzimidazole or benzotriazole ring or with a 6-membered heterocyclic ring, e.g a pyrazine, quinoxaline or morpholine ring.

Simplified, advantageously usable compounds can be represented according to the invention, for example, by the following structural formulae:

wherein R stands for an aliphatic residue or a residue of an aliphatic nature with preferably 6 - 30 Catoms, N represents a possibly quaternary nitrogen atom in a 5- or 6-membered ring, and X stands for a second heteroatom, e.g. a nitrogen, oxygen or sulphur atom. If the nitrogen atom N is present as a quaternary nitrogen atom, then the compound comprises an anion, such as is typical of cation-active, surface-active compounds. The benzene nucleus of formula (2) may possibly be substituted, e.g. by alkyl or hydroxyalkyl residues and/or halogen atoms.

Examples of advantageous heterocyclic compounds usable according to the invention are:1.) Imidazole derivatives of the formula:

wherein R is an aliphatic residue, more especially an alkyl residue with 6 to 30 C-atoms; Rq and R2 are hydrogen atoms, alkyl or hydroxyalkyl residues, more especially alkyl or hydroxyalkyl residues with 1 - 5 C-atoms; and A- is an anion, such as is typical of cation-active, surface-active compounds.

Typically, R may stand, for example, for an alkyl residue with 12 - 18 C-atoms, R1 and R2 are methyl or ethyl residues and A9i stands for a residue of the formula - OSO3R3, wherein R3 is an alkyl residue with preferably 1 - 5 C-atoms, or for a halogen atom.

2.) Benzimidazole derivatives of the formula:

wherein R, Ra, R2 and AD have the meaning already indicated Typically, R stands for a residue of the formula -C17H3s, Rl and R2 are methyl residues and A3 stands for an anion of the formula - OSO3CH.

3.) Morpholine derivatives of the formula:

wherein R stands for an alkyl residue with 1 - 30, preferably 6 - 30 C-atoms.

4.) Quaternary morpholine derivatives of the formula:

wherein R, R1 and Am have the meaning already indicated.

5.) Imidazoline derivatives of the formula:

wherein R, Rl, R2 and A- have the meaning already indicated. Typically, R stands, for example, for an alkyl residue with 12 - 18 C-atoms, R1 is a methyl residue, R2 is a residue of the formula -C2H4OH and AO stands for a chloride ion.

The quantities of the compounds or compound mixtures used according to the invention depend on the recipe for the respective linoleum quality and on the point in time at which the addition is made.

The incorporation of the antistatic additive according to the invention is preferably effected when the individual components of the linoleum recipe are present as a non-dusting cohesive structure, namely, for example, in the second screw extruder. The quantity of the antistatic additive according to the invention to be added is here preferably between 0.5 and 15 % by weight related to the total recipe.

The object of the following examples is to illustrate the invention in more detail.

Example 1 {Comparison example) For comparison purposes, a linoleum web was produced in known manner from: 17 parts wood flour 13 parts pigments 33 parts Bedford cement 21 parts cork powder 16 parts scrap flour The electric leakage resistance of this linoleum web was at: RA > 1011 Ohm.

Example 2 (Comparison example) For comparison purposes, another linoleum web was produced from: 50 parts wood flour 45 parts conductive carbon black 157 parts Bedford cement 15 parts neutral mixing compound 30 parts cork powder The electric leakage resistance of this linoleum web was at: RA 5 x 106 Ohm. However, the linoleum web was black, and there did not exist any colouristic design possibilities.

Example 3 {Comparison example) For comparison purposes, another linoleum web was produced, using a standard antistatic agent, from: 17 parts wood flour 13 parts pigments 33 parts Bedford cement 21 parts cork powder 16 parts scrap flour 5 parts of a standard nitrogenous polyglycol based antistatic agent Leakage resistance RA: 6.8 x 107 Ohm with fresh linoleum and RA: 1.7 x 1010 Ohm with ripened linoleum.

This example shows that the antistatic agent used loses its effectiveness as a result of the ripening process of the linoleum.

Example 4(Comparison example) For comparison purposes, another linoleum web was produced, using another standard antistatic agent, from: 150 parts wood flour 106 parts pigments 280 parts Bedford cement 180 parts cork powder 135 parts scrap flour 43 parts of a standard fatty acid polyglycol ester based antistatic agent Leakage resistance with fresh linoleum: RA 3.3 x 10 8 Ohm.

The ripening period of the linoleum without an antistatic agent was 20 days. The ripening process with the antistatic agent 318 S was stopped after 40 days - no satisfactory ripening progress was ascertained.

Example 5 A linoleum web was produced from: 100 parts wood flour 22 parts pigments 136 parts Bedford cement 30 parts neutral mixing compound 30 parts cork powder 10 parts antistatic agent: N-stearyl-N-ethyl morpholinium ethyl sulphate Leakage resistance: Fresh linoleum RA 4 x 107 Ohm Ripened linoleum RA 8.5 x 107 Ohm Ripening period without the antistatic agent: 19 days Ripening period with the antistatic agent: 19 days Example 6 A linoleum web was produced from: 100 parts wood flour 20 parts pigments 136 parts Bedford cement 30 parts neutral mixing compound 30 parts cork powder 16 parts antistatic agent as indicated in example 5 Leakage resistance:Fresh linoleum RA 1.4 x 107 Ohm Ripened linoleum RA 8 x 107 Ohm Ripening period without the antistatic agent: 19 days Ripening period with the antistatic agent: 20 days Example 7 Another linoleum web was produced from: 150 parts wood flour 106 parts pigments 280 parts Bedford cement 180 parts cork powder 135 parts scrap flour 26 parts antistatic agent of the formula:

Leakage resistance: Fresh linoleum RA 5 x 107 Ohm Ripened linoleum RA 8 x 107 Ohm The ripening period of the linoleum was 24 days.

Example 8 Another linoleum web was produced from: 100 parts wood flour 20 parts pigments 136 parts Bedford cement 30 parts neutral mixing compound 30 parts cork powder 10 parts antistatic agent: Imidazoline compound of the formula:

with R = -residue of coconut fatty acid Rl = CH? Leakage resistance: Fresh linoleum RA 1.5 x 107 Ohm Ripened linoleum RA 5 x 107 Ohm The ripening period of the linoleum was 22 days The examples 5 to 8 show that the use of the heterocyclic compounds employed according to the invention is advantageous.

Claims (10)

1. A conductive linoleum web with a content of an additive which improves the conductive and antistatic properties of the web, characterised in that it contains as the additive at least one compound with at least one heterocyclic ring which comprises at least one nitrogen atom and at least another heteroatom.

2. A conductive linoleum web as claimed in Claim 1, characterised in that it contains at least one compound with at least one heterocyclic ring which, in addition to the nitrogen atom, contains as another heteroatom either another nitrogen atom or an oxygen atom.

3. A conductive linoleum web as claimed in Claims 1 and 2, characterised in that it contains a heterocyclic compound of the indicated type which comprises at least one aliphatic residue with at least 6 Catoms.

4. A conductive linoleum web as claimed in Claim 1, characterised in that it contains a derivative of imidazole, imidazoline or morpholine as the heterocyclic compound.

5. A conductive linoleum web as claimed in one of Claims 1 to 4, characterised in that it contains the heterocyclic compound or a mixture of the heterocyclic compounds in a quantity of 0.5 to 15 % by weight.

6. A conductive linoleum web as claimed in one of Claims 1 to 5, characterised in that the web is a single-layer web.

7. A conductive linoleum web as claimed in one of Claims 1 to 5, characterised in that the web is a multiple-layer web.

8. A conductive linoleum web as claimed in Claim 7, characterised in that it comprises a bottom layer consisting of a composition based on coarse-grain cork powder (Korkment).

9. A conductive linoleum web as claimed in one of Claims 1 to 8, characterised in that it contains cork granules as the filler.

10. A conductive linoleum web substantially as hereinbefore described with reference to and as illustrated by the examples herein set forth.