GB2398007A

GB2398007A - Insect proofing of carpets

Info

Publication number: GB2398007A
Application number: GB0329605A
Authority: GB
Inventors: Ian Palmer
Original assignee: Second Nature UK Ltd
Current assignee: Second Nature UK Ltd
Priority date: 2003-01-14
Filing date: 2003-12-17
Publication date: 2004-08-11
Anticipated expiration: 2023-12-17
Also published as: GB0300797D0; GB0329605D0; GB2398007B

Abstract

A method of protecting carpets from insect attack, in which Diatomaceous Earth (DE) is incorporated into the deep pile in the area of the backing, employs the steps of:- <SL> <LI>i) applying diatomaceous earth particles to the backing of a carpet; <LI>ii) fitting the pile through the backing; and <LI>iii) applying a film of thermoplastic polymeric material to the back of the carpet. </SL> DE is added to the backing, either before the pile is fitted or afterwards and retained in / on the backing, e.g. by electrostatic or adhesive means. Alternatively the DE may be added to the pile either before, or during, the pile fitting process. The DE is secured in position by the application of a hot liquid thermoplastic polymeric material so that it flows in and around the backing and the pile fibres and wets at least a part of the surfaces of the particles and, when cool, forms a film, binding the backing and pile fibres together and holding the particles with at least a part of their surfaces exposed.

Description

INSECT PROOFING OF CARPETS

This specification relates to a method and apparatus for applying permanent insect proofing to carpets, rugs and the like.

Various methods of insect proofing natural fibres, such as wool, are known and these have been applied to the protection of carpets. In the case of carpets, this protection has been of short duration and, even when re-applied on a regular basis, does not give complete protection to the deep fibres near the backing.

WO 91/19038 A1 teaches the use of an active ingredient, such as permethrin, in or on inert carrier particles, such as talc, chalk powder or polymeric powders. The treated powder is spread evenly over the cloth or carpet and agitated to distributed it within the fibres and then the whole is heat treated. Where the carrier is thermoplastic, heating will dissolve the permethrin in the polymer and melt the mixture onto the carpet fibres. Where the carrier is inert, the permethrin is melted onto the particle surfaces and onto the fibres. In either case, the permethrin is volatile and will sublime over a period of time. Before this happens, the carrier particles may be removed by vacuuming, or shampooing, the carpet. Thus the protection is of short-term duration. A similar process is taught in JP 2 047 374 A, with the same weaknesses.

Surface treatments are known, e.g. JP 63-264 506 A, but these use volatile chemicals and require application by specialists, wearing breathing apparatus. Many people find this type of treatment unacceptable and the residual smells objectionable. Such surface treatments rarely get down to the base of the pile or where the pile goes into the backing and this leaves a haven in which moth larvae can develop. Vacuuming, particularly if accompanied by beating of the carpet, can be effective against larvae in the upper part of the pile but does not normally remove those living deep in the pile fibres in the area of the backing.

GB 2 370 224 A teaches the use of Diatomaceous Earth (DE), in powder form, as a permanent insect proofing agent. It may be introduced into the fibres during either the scouring, pre-manufacturing or manufacturing processes. The DE is best added after operations, such as opening the fibres, where it is known that electrostatic charges are generated on the fibres, and, it is believed, that these charges hold the DE particles onto the fibres.

e;:: le::: .e e. ::e es a Àe ee If the fibres are made into the finished article before the electrostatic charges have leaked away, the DE Will be retained, intimately mixed with the fibres. If the application does not involve disturbing the fibres, the DE will provide protection throughout the life of the article.

Suitable applications are thermal insulation in lofts and walls, wadding in chairs, beds, padded coats, etc. DE particles held to carpet fibres by electrostatic charges or surface roughnesses would not provide protection when the carpet was vacuumed or shampooed, unless there was a means of securing them permanently into the carpet matrix. There is thus a need to provide a means by which DE particles may be secured permanently to carpet fibres and / or to the backing.

According to the invention, there is provided a method of protecting carpets from insect attack comprising the steps of: i) applying diatomaceous earth particles to the backing of a carpet; ii) fitting the pile through the backing; and iii) applying a film of thermoplastic polymeric material to the back of the carpet; characterized in that the diatomaceous earth particles are retained in the area of the backing during the pile fitting stage and that the thermoplastic polymeric material is applied hot, in a liquid form, so that it flows in and around the backing and the pile fibres and wets at least a part of the surfaces of the diatomaceous earth particles so that, when cool, the thermoplastic polymeric material forms a film, binding the backing and pile fibres together and holding the diatomaceous earth particles with at least a part of their surfaces exposed.

According to a first variation of the method of the invention, the diatomaceous earth is applied to the backing before the pile has been tiffed.

According to a second variation of the method of the invention, the diatomaceous earth is applied after the pile has been fitted.

According to a third variation of the method of the invention, the diatomaceous earth is added to the pile fibre either before, or during the pile fitting process.

According to a fourth variation of the method of the invention, the means of applying diatomaceous earth to the backing, or pile fibre, involves the use of electrostatic charges.

À : A: e: 1 À C À À À À À À . . . According to a fifth variation of the method of the invention, means to urge the diatomaceous earth particles into the substrate of the backing are provided.

According to a sixth variation of the method of the invention, the means to urge the diatomaceous earth particles into the substrate of the backing is applying simultaneous pressure to both sides of the backing.

According to a seventh variation of the method of the invention, the means to urge the diatomaceous earth particles into the substrate of the backing is vibration.

According to an eighth variation of the method of the invention, the diatomaceous earth is applied to the backing after the backing has been treated with an adhesive compound and before the pile has been fitted.

According to a ninth variation of the method of the invention, the diatomaceous earth contains silicon dioxide in the form of silica gel.

According to a tenth variation of the method of the invention, the diatomaceous earth contains sodium sulphate.

In a preferred application of the method of the invention, the carpet manufacturing process is that used to make dense pile Axminster carpets. Here intricate patterns are made up from a number of bobbins, each wound with coloured fibres to fomm a single line of the pattern, and offered to the carpet making head in a predetermined order to create the pattem. In this case, the fibres are fitted through the backing mesh in a series of U-shaped loops before the loops are secured to the backing by the application of a hot liquid thermoplastic polymer.

When the polymer cools and solidifies, it holds the individual fibres to the backing member.

The principle of the invention is that DE particles are incorporated into the zone of the backing so that a proportion of them will be held in place by the polymer. Ideally, a large proportion of the DE particles will be wetted by the polymer on only a part of their surface so that the rest of the surface is exposed. Experiments show that insect larvae shun DE and will move as far away from a DE particle as possible. DE does not have a smell that humans can detect and does not evaporate. It appears to deter larvae because it can become attached to the cuticle between the segments of the insects' bodies. This then appears to kill them by desiccation.

s: of: d: À. : :: .: DE particles, with free surface, will certainly deter moths from laying eggs and drive away any larvae, which do hatch. If there is an adequate number of DE particles in the backing zone of the carpet, this will prevent insect attack in the deep pile, forcing the larvae into the upper part of the pile, where vacuuming is likely to remove them. Thus, protection of the backing / deep pile zone of a carpet by the method of the invention, combined with regular vacuuming, should protect the whole depth of the carpet permanently from insect attack.

Some of the DE particles are likely to become completely embedded in the polymer film.

Whether these have a deterrent effect will have to be proven. Some particles will miss the polymer and subsequently be lost. It is thus necessary to apply more than the minimum concentration required and the necessary excess can be determined by experiment.

DE particles may be added either before the pile is tiffed into the backing or after it has been fitted. Adding the DE before tiffing should allow DE particles to become located on both sides of the backing but some of these particles could be lost when the pile is tiffed. A preferred method of adding DE before tiffing the pile is to treat the backing with and adhesive and sprinkle on the DE while the adhesive is still tacky. If the DEis added after tiffing, there is greater likelihood of particles becoming completely embedded in the polymer film.

Whichever method is chosen, excess DE may be added to compensate for that lost or unavailable as a deterrent. It is believed that electrostatic charges attract DE particles and so the use of means to generate such charges in the carpet backing prior to the application of the DE powder should increase the level of DE incorporated into the backing.

Another alternative is to add DE to the fibres before, or during, the carpet making process. In this case, the DE may be affected to, and held onto, the fibres by electrostatic charges. The relative movement between fibre and backing during tiffing the pile will generate further charges, thus retaining the DE particles until the thermoplastic polymeric backing is applied.

For a clearer understanding of the invention and to show how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which: Figure 1 is a block diagram of a carpet making process, showing methods by which the invention may be incorporated into the process; Figure 2 is a section through a carpet and its backing, showing the various stages of its manufacture; and Figure 3 is a section through the thermoplastic polymer film, binding the carpet fibres to the backing and showing the location of the DE insect proofing particles.

À : .: *: :: e; In the following description, the same reference numeral is used for the same component or for different components fulfilling identical functions.

Referring to Fig. 1, a roll of carpet backing 1 is uncoiled 2 and moved 11 through the carpet manufacturing process. This process consists of inserting the pile 9 and applying a hot thermoplastic backing from a liquid source 16 via an intermediate roller 17 to an applicator roller 18. This applies a thin film 21 (Fig. 2) of liquid polymer to the backing which solidifies to bind the pile fibres 1 OA to the backing matrix 2.

The DE powder may be added either before the pile has been looped through the backing or after the pile has been fitted and before the thermoplastic polymer is applied. Both options are shown in Fig. 1. In the first option an electrostatic charge generator 3 is used to brush backing 2 and create electrostatic charges in the backing member. Equal and opposite charges, which are produced in generator 3, are conducted to earth 4. DE powder is then sprinkled 5A onto the backing 2 and individual particles 20 (Fig. 2) held to the fibres 2A, 2B of the backing 2 by electrostatic attraction. This is shown happening over a table 6 so that DE powder, which falls through backing matrix 2, is swept along 11 and caught in a tray 8A for further use. A counter roller 7 presses backing 2 on to table 6 so that the DE powder is forced, where possible, between the fibres of backing 2. A further means of increasing the DE take up by the backing is to vibrate table 6 (by a means not shown).

Electrostatic generator 3A acts on the underside of backing 2 but static electricity should give charges throughout the whole of the backing member. The DE particles 20 (Fig. 2) are very small typically 5-1 O,um and will be attracted by the electrostatic charges and held in intimate contact with the fibres of the backing member 2. Generator 3A may be located above the backing 2 if this gives a better static charge distribution. Pressure 7, 6 and t or vibration 6 will give an even distribution of DE throughout the thickness of backing 2.

The backing 2, with its DE powder incorporated, passes to piling machine 9 which feeds wool fibres through the backing and cuts them off as U- shaped loops (Section C, Fig, 2). This process of passing wool through backing 2 may generate further static electric charges and piling machine 9 is earthed 4 to retain any such charges in the wool and backing. From piling machine 9, the carpet, with the pile shown as 10, passes round a roller 12 towards the polymer applying stages. s

t' :- e' B: a. :, Be. e:. :. ese ee.

A second place where DE powder may be added is between the piling 9 and thermoplastic filming 18 stages. This may be accomplished with an electrostatic generator 3B brushing backing 2. As the pile 10 is only fitted in as U-shaped loops 1 OA, care must be taken that the brushing action of generator 3B does not pull out any fibres. Carpet 10 then passes between S a roller 13 and counter roller 14, with the powder being admitted 5B in to the angle of nip between roller 13 and the carpet backing 2. Though roller 13 and carpet 10 are moving away from the point of particle addition, a small pile of DE should build up in the angle between roller 13 and backing 2 allowing the electrostatic charges to attract particles into the backing fibres. DE may adhere to roller 13 and be carried round the circumference and be pressed into the ends of the loops 1 OA (Fig. 2) and backing 2. Tray 8B catches any DE, which drops off roller 13.

The carpet then continues to the polymer filming stage. Here, heated liquid polymer 16 in a trough 15 is transferred to a first heated roller 17, dipping into liquid 16. A film of polymer is carried round the circumference of roller 17 and transferred to a second heated roller 18 and thence to the backing 2 of carpet 10. (In some processes, intermediate roller 17 is omitted and roller 18 dips directly into trough 15.) The pressure of the contact between roller 18 and backing 2 forces the film of polymer into the woollen pile and backing so that, when the polymer cools and solidifies, the pile is secured into the backing member. The carpet 19 then passes to the finishing stages, e.g. cutting the fibres to a uniform length, inspecting and replacing missing fibres, etc. Fig. 2 shows the various stages of the carpet manufacturing process in a sectional diagrammatic form. The backing is shown as a warp 2A and a weft 2B. Two fibres are shown for the weft 2B as this is often the case to give a strong backing 2. Section A shows the backing before any processing has taken place. Section B shows the backing after exposure to electrostatic generator 3A and addition of DE powder 5A with particles of DE powder shown as black spots 20. Section C shows the addition of pile fibres 10A in the form of U-shaped elements. As shown, each U-shaped fibre passes round a pair of weft fibres 2B. DE powder particles 20 are shown amongst these fibres.

Section D shows the effect of the addition of the polymeric film 21, which binds fibres 10A to backing members 2A and 2B. Film 21 moves via capillary attraction and the pressure of roller 18 through the backing 2 to grip pile fibres 10A and DE particles 20.

#he À e.e l: 4 Be, * e. e ' e À Fig. 3 shows a representation of the aim of the invention with polymeric film 21 gripping DE particles 20. Ideally, particles 20A will be held by only a part of the circumference so that there is free surface available to act as a deterrent to moths, who might want to lay eggs in the carpet and to any larvae that might hatch from any eggs which are laid. Some particles 20B will become completely embedded in film 21 and these may also have a deterrent effect.

An additional benefit of the method of the invention is that some of the DE particles 20 (Fig. 2) may be incorporated into the backing 2 zone of the carpet but are not held by film 21, e.g. the particles numbered 20 in Section D. Because such particles are in the deepest part of the pile 10, they will be least affected by vacuuming or shampooing and the natural surface roughnesses of particle 20 and the pile fibres 10A and backing fibres 2A and 2B may combine to retain them permanently in the carpet to add to the permanence of the insect proofing.

Addition of DE has been taught either before the pile is fitted 5A, or afterwards 5B. However, it may also be added during the pile fitting stage 9. This is indicated by arrow 5C and may be complemented by a collection tray 8C. The precise details of how the DE would be added 5C would depend on the design of the actual fitting head 9. It could also be added to the fibre before it is made up into bobbins (not shown).

It should be noted that addition of DE particles by the method of the invention into / through the backing 2, or at the pile fitting stage 9, and securing it in place is very different to the - sprinkling of powder onto the surface of the carpet and brushing into the pile. In the later case, the powder is in the top of the pile and greatly affected by vacuuming and shampooing.

However, DE particles added by the method of the invention are in the very deepest of the pile and so least affected by vacuuming. Furthermore, the deepest pile is where the fibres are most tightly packed together and where DE particles will be most difficult to dislodge.

To protect fibres from insect attack, effective DE powder is required at a rate of about 1% by weight, i.e. particles 20A (Fig. 3). To allow for losses in the manufacturing process, particles 20B, which become totally embedded in film 21 and particles 20, which are not held by film 21 and may subsequently be lost by vacuuming, etc., significantly more DE powder should be used, e.g. 2 or 3% by weight. Much of this excess should recovered in trays 8 for re-use.

t Il; t'd:' t:: .:e:e..'c' The application of the invention has been taught during the actual carpet manufacturing process itself. However, it is also applicable before the carpets are made, i.e. directly to the backing. For example, after the warp 2A and weft 2B have been woven, the completed backing 2 could be sprayed with a mist of an adhesive and, before it dries, DE would be sprinkled onto backing 2. This would give DE particles 20A stuck onto the adhesive surface rather than embedded in it 20B. The adhesive is dried before the backing is coiled up 1.

It is a part of the applicant's philosophy not to use artificial or noxious substances in their products and water-based adhesives, e.g. based on starch, are preferred. However, organic adhesives or warmed thermoplastic polymers, which have no residual smell and which are I applied well away from the plant operating personnel, are acceptable.

The method of the invention relies on a purely naturally occurring compound, or mixture of compounds, which give protection solely by physical processes. There is thus no active ingredient to sublime and no smells. The protection will thus last for the lifetime of the carpet. This provides a totally new dimension in the permanent insect proofing of carpets.

Claims

tt. ::: I' t: ,'.' :' I err Ire À What we claim is: 1 A method of

protecting carpets from insect attack comprising the steps of:- i) applying diatomaceous earth particles to the backing of a carpet; S ii) fitting the pile through the backing; and iii) applying a film of thermoplastic polymeric material to the back of the carpet; characterized in that the diatomaceous earth particles are retained in the area of the backing during the pile fitting stage and that the thermoplastic polymeric material is applied hot, in a liquid form, so that it flows in and around the backing and the pile fibres and wets at least a part of the surfaces of the diatomaceous earth particles so that, when cool, the thermoplastic polymeric material forms a film, binding the backing and pile fibres together and holding the diatomaceous earth particles with at least a part of their surfaces exposed.
2 A method of protecting carpets from insect attack, as claimed in claim 1, wherein the diatomaceous earth is applied to the backing before the pile has been fitted.
3 A method of protecting carpets from insect attack, as claimed in claim 1, wherein the diatomaceous earth is applied after the pile has been fitted.
4 A method of protecting carpets from insect attack, as claimed in claim 1, wherein the diatomaceous earth is added to the pile fibre either before, or during the pile fitting process.
A method of protecting carpets from insect attack, as claimed in claims 2 - 4, wherein the means of applying diatomaceous earth to the backing, or pile fibre, involves the use of electrostatic charges.
6 A method of protecting carpets from insect attack, as claimed in claim 5, wherein means to urge the diatomaceous earth particles into the substrate of the backing are provided.
7 A method of protecting carpets from insect attack, as claimed in claim 6, wherein the means to urge the diatomaceous earth particles into the substrate of the backing is applying simultaneous pressure to both sides of the backing.
8 A method of protecting carpets from insect attack, as claimed in claim 6, wherein the means to urge the diatomaceous earth particles into the substrate of the backing is vibration.

: : .: : : : : : À : À À À À
9 A method of protecting carpets from insect attack, as claimed in claim 2, wherein the diatomaceous earth is applied to the backing after the backing has been treated with an adhesive compound and before the pile has been fitted.
10 A method of protecting carpets from insect attack, as claimed in any preceding claim, wherein the diatomaceous earth contains silicon dioxide in the form of silica gel.
11 A method of protecting carpets from insect attack, as claimed in any preceding claim, wherein the diatomaceous earth contains sodium sulphate.
12 A method of protecting carpets from insect attack, as described in and by the above statement with reference to the accompanying drawings.