GB2360289A

GB2360289A - Olefinic polymers with enhanced anti-static properties

Info

Publication number: GB2360289A
Application number: GB0106202A
Authority: GB
Inventors: Alex Celik; Gary John Wilson
Original assignee: Amtico Co Ltd
Current assignee: Amtico Co Ltd
Priority date: 2000-03-14
Filing date: 2001-03-14
Publication date: 2001-09-19
Also published as: GB0005992D0; GB0106202D0

Abstract

An olefinic polymer is compounded with a solid anti-static agent before further processing of the polymer. The polymer may be a homopolymer, a copolymer of an olefinic and a second polymerisable species, an olefinic-based terpolymer or a higher polymer. The anti-static agent is preferably an anionic surfactant. The anti-static agent is preferably present in an amount of up to 10% by weight of the polymer. Also disclosed are articles, e.g. a floor covering or floor tile comprising one of the compounded olefinic polymers. The olefinic polymer may be an ionomer.

Description

OLEFINIC POLYMERS WITH ENHANCED ANTISTATIC PROPERTIES This invention relates to olefinic polymers with enhanced antistatic properties and to articles made from or including said polymers. The term "polymer" herein is intended to include homopolymers, copolymers and ter- or higher polymers, especially copolymers of olefins and unsaturated acids, known as ionic copolymers (ionomers). The present invention will therefore be described herein with particular reference to olefinic ionic copolymers (ionomers), although it is not to be construed as being limited thereto.

Ionomers can be treated in accordance with most of the currently-available plastics processes. The inherent optical transparency of many ionomers makes them ideal for use, after appropriate processing, as films (e.g. for wrapping foodstuffs) or as protective outer layers (e.g. "wear-layers" for tiles and similar flooring components). In both of the aforesaid applications, the relatively high "surface resistivity" of the ionomers gives rise to increased electrostatic charging ("static") and therefore to inconvenience for the user.

The use of "anti-static" preparations is well known per se. Such preparations can be "internal" (i.e. compounded with the polymers before further processing) or "external" (i.e. applied, usually in aqueous solution, to the outer surface of the finished product).

Many currently-available antistatic agents for internal compounding with olefinic polymers are usually liquids. These tend to migrate to the surface of the finished product. While solid antistatic agents are known, their use in connection with olefinic polymers has often hitherto been limited to the external application of an aqueous solution of the antistatic agent to the outer surface of the finished product.

Consequently, the antistatic properties of flooring components having an ionomer "wear layer" which has been compounded with a liquid anti static agent or which has been treated by the external application of an aqueous solution of a solid antistatic agent can quickly deteriorate as a result of cleaning and/or wear and tear.

The Applicant has unexpectedly found that ionomers can be formulated with an internally-mixed, solid, antistatic agent and that subsequent processing of the so-formulated ionomers provides articles with improved antistatic properties.

Accordingly, the present invention provides an olefinic polymer which has been compounded with a solid antistatic agent before further processing of said polymer.

The present invention also provides an article comprising at least one olefinic polymer as defined in the immediately-preceding paragraph.

The olefinic polymer may be a homopolymer, a copolymer of an olefin and a second polymerisable species, an olefin-based terpolymer or a higher polymer.

In a particularly preferred embodiment of the present invention, the olefinic polymer is a copolymer of an olefin and a metal salt of an unsaturated carboxylic acid, such copolymers being known per se by the term "ionic copolymer" or "ionomer". Suitable ionomers include copolymers based on ethylene and methacrylic or acrylic acid (especially the zinc salt) which are available under the Registered Trade Marks SURLYN and IOTEK respectively.

Compounding of the polymer with the antistatic agent is carried out by any convenient method, such as mixing in an internal (e.g. Banbury) mixer or in an extruder. The compounded polymer may then be pelletised or granulated for further processing. Alternatively, the polymer and the antistatic agent may be compounded with a further plastics material to form a masterbatch.

Preferably, the antistatic agent consists essentially of a surfactant, in particular an anionic surfactant, for example an alkali metal salt of a C,o- C,B alkyl sulphonate, a C,o- C,8 alkyl benzene sulphonate or a C,o- C,$ alkyl polyoxyethylene sulphonate. A suitable anionic surfactant for this purpose is available as DEHYDAT 93P. (DEHYDAT is a Registered Trade Mark).

The antistatic agent may be present in the compounded polymer in an effective amount of up to 10% (e.g. about 5%) by weight of the polymer. The enhanced antistatic properties of polymers in accordance with the present invention may conveniently be determined by measurement of the static electrical propensity of an article having an outer surface comprising the polymer, relative to a control sample.

The present invention will be illustrated by way of the following example: The "Walking Test" according to ISO Draft International Standard 6356, in which the static electrical charging associated with soling materials commonly found on footwear is determined, was carried out on the following flooring samples: CONTROL SAMPLE: Flooring tiles with ionomer (SURLYN) wear layer, in which the ionomer was compounded with about 5% to 10% by weight of a liquid antistatic agent.

TEST SAMPLE: Flooring tiles with ionomer (SURLYN) wear layer, in which the ionomer was compounded with 5%by weight DEHYDAT 93P.

SOLING MATERIALS: Rubber, p.v.c., Neolite. The following results were obtained:

Sample Soling: Rubber P.V.C. Neolite Static Electrical Propensity (kV) Control +5.4 +5.0 +5.8 Test +3.1 +3.6 +2.5

Claims

CLAIMS 1. An olefinic polymer which has been compounded with a solid anti static agent before further processing of said polymer.
2. An olefinic polymer according to Claim 1 wherein the olefinic polymer is a homopolymer, a copolymer of an olefin and a second polymerisable species, an olefin-based terpolymer or a higher polymer.
3. An olefinic polymer according to Claim 1 or Claim 2 wherein the olefinic polymer is a copolymer of an olefin and a metal salt of an unsaturated carboxylic acid.
4. An olefinic polymer according to Claim 3 wherein the copolymer is based on ethylene and methacrylic or acrylic acid.
5. An olefinic polymer according to Claim 4 wherein the copolymer is based on ethylene and the zinc salt of methacylic acid or the zinc salt of acrylic acid.
6. An olefinic polymer according to any preceding claim wherein the antistatic agent consists essentially of a surfactant.
7. An olefinic polymer according to Claim 6 wherein the surfactant is an anionic surfactant.
8. An olefinic polymer according to Claim 7 wherein the anionic surfactant is an alkali metal salt of a C,,.- C,e alkyl sulphonate, a C,a- C,e alkyl benzene sulphonate or a C,o- C,8 alkyl polyoxyethylene sulphonate.
9. An olefinic polymer according to any preceding claim wherein the antistatic agent is present in the compounded polymer in an effective amount of up to 10% by weight of the polymer.
10. An olefinic polymer according to any preceding claim wherein the antistatic agent is present in the compounded polymer in an effective amount of about 5% by weight of the polymer.
11. An article comprising at least one olefinic polymer according to any preceding claim.
12. An article according to Claim 11 wherein the article comprises a floor covering or a floor tile.
13. An olefinic polymer substantially as described herein and with reference to the example.
14. An article substantially as described herein and with reference to the example.