AND TEXTILES

This invention relates to a method of treating carpets and other textiles made from animal fibres, the method improves resistance to damage caused by insects.

Present methods of treating wool and other animal fibres to be resistant to attack from insects involve treating the fibres with insecticides such as synthetic pyrethroids, most commonly permethrin. Wool fibres are commonly treated in a loose wool scour, in a dyebath, during tape scouring or chemical setting of yarn produced from the fibres by adding an aqueous insecticidal emulsion to a dyebath or a scouring bowl. Much of the active insecticidal ingredient exhausts onto and into the animal fibres. In the case of application during a dyeing cycle where the liquor is boiled, typically 95% of the insecticide is taken up by the fibres. Scour bowl (loose wool or yarn) applications are normally run using a continuous exhaustion process where the aim is to keep the concentration of insecticide in the bowl constant.

In both of the above cases there are considerable concentrations of insecticide in effluent produced by the process, particularly when a scour bowl, is discharged at the end of a scouring run.

Such effluent concentrations of insecticides are undesirable environmentally in that significant concentrations may remain after sewage or other waste treatment. These concentrations may have adverse effects on the population of aquatic insects in waters to which the treated effluent is discharged. This may have an adverse impact on fish species.

The problem is particular severe in parts of the U.K. where very strict limits have been set on insecticide levels in effluent. In one particular area (Severn-Trent Water Authority) these controls are so strict that effluent from traditional insect-resist treatment methods cannot meet the levels imposed by the Water Authority at normal textile-mill dilutions.

In broad terms the object of this invention is to provide a method of applying insect-resist agents to animal fibres or products made thereof which minimises the production of liquid effluents thus overcoming environmental problems associated with conventional techniques.

Further objects and advantages of the invention will become apparent from the following description which is given by way of example only.

According to the present invention a method is provided whereby insect-resist active compounds are applied to animal fibres (for example wool) or products thereof (for example carpets) using a largely dry technique.

In this method the active insect-resist compound is applied to inert particles or incorporated within carrier particles or polymeric particles which are low melt/steam fusible and which are applied evenly over the animal fibres or product thereof.

The carrier particles can typically consist of talc, diatomaceous earth, ground corn cob material, chalk or polymeric powders for example polyester, or polyamide or

ethylene/vinyl acetate powders preferably with a proportion of its particles less than 7 um in diameter.

The active insect-resist compound can be dissolved in a solvent, the carrier particles are then added, the solvent is then evaporated to leave the active ingredient sorbed onto the particles surfaces or within the polymer particles. Alternatively the active insect-resist compound can be incorporated into the polymer prior to powdering.

The treated particles are then spread evenly onto the animal fibres typically by a sprinkling operation which is followed by mechanical agitation of the fibres to improve particle distribution. At this stage the invention preferably includes a heat or steaming step in which the fibres or product thereof are heated or steamed for a period of up to 3-4 minutes. This step fuses particles of the polymer type, for example polyamides, to the fibre or to the carpet backing mat. This step markedly improves fastness to subsequent vacuuming, wet or dry-cleaning and light exposure. Steaming also improves fastness of inert non-fusible particles in that it improves the affinity of the particles for the animal fibres.

Further aspects of the invention will now be described by way of example only.

The examples are provided as illustrations of the method:

Example 1.

Talc was treated with permethrin by dissolving the permethrin in petroleum ether, adding the talc and removing the solvent by rotary evaporation to dryness.

The talc specification were: median particles size (population distribution) 7.4 μm median particles size (population distribution) 8.6 urn median particle size (population distribution) 7.1 μm

The permethrin used was 93.7% pure with a 25.75 cis: trans iso er ratio.

The permethrin was applied to the talc at a rate of 1.25g/100g of talc.

The treated talc was applied to a wool carpet (669 tex, /8th gauge, 8mm pile length, 36 stitches/dm) by sprinkling the treated talc evenly over the carpet pile at a rate of 2% treated talc on weight of pile. This was then brushed to assist penetration of the talc down and into the pile.

One half of the carpet sample was then steamed using atmospheric pressure steam for 5 minutes.

Both samples were then vacuumed thoroughly to remove excess talc.

Samples of the carpet pile were then analysed for permethrin content before and after 3 hot water extraction shampooings using a commercial low foam shampoo at 1% /v concentration.

Results were as follows:

unsteamed carpet before shampooing 0.005% permethrin unsteamed carpet after shampooing 0.002% permethrin

steamed carpet before shampooing 0.022% permethrin steamed carpet after shampooing 0.016% permethrin

This example illustrates the beneficial effect of steaming in the transferring of the permethrin to the wool fibres of the carpet. Less than 30% of the permethrin is lost during the three shampooing cycles which is comparable to the loss expected in shampooing carpet insect-resist treated using conventional aqueous exhaustion methods.

Analysis of the talc vacuumed from the steamed carpet gave a permethrin content of 0.39% which is lower than that in the talc applied to the carpet (1.25%).

Example 2

Talc (as in example 1) was treated with 1.25% /w permethrin as for Example 1.

Three carpets of different constructions were sprinkled with the treated talc at the same nominal application rate (2% treated talc on mass of pile) followed by steaming for 5 minutes.

The carpets were vacuumed and half of each was shampooed as before (3x hot water extraction cleanings). Additionally the shampooed carpets were exposed to an artificial light source to simulate sunlight to assess any loss of permethrin caused by light degradation. The method used was as outlined in International Wool Secretariat Test Method 28 (IWS TM28).

Results were as follows:

Carpet Permethrin Permethrin Permethrin Fastness Construction Content Content Content Factor After After After Vacuuming Shampooing Shampooing and

(%oww) (%oww) Lightfastness

Testing

(%oww)

A. Loop

Pile 0.019 0.018 0.015 0.77

669 tex 5 /32 gauge,

5mm pile height

B. Cut Pile 669 tex 0.023 0.019 0.019 0.91

/8 gauge, 8mm pile height

C. Cut Pile

669 tex 0.025 0.020 0.019 0.76

/8 gauge, 12mm pile height

* 0.25% permethrin on total wool weight applied

* According to IWS TM28

The permethrin content of the pile tip, centre and base were analysed for carpet C (12mm pile height). These analyses were repeated for the same carpet sprinkled with a superfine treated talc (90% of particles by mass less than 5 urn and 50% of particle less than 2 um) .

The result were;

Percentage Permethrin At: Tip Centre Base

Coarser talc 56 26 18 Superfine talc 47 29 24

These test results indicate that there is sufficient permethrin content at the base of the pile to be effective even in a long pile carpet.

Carpet A and C treated with permethrin containing talc were subjected to wear testing consisting of up to 8000 revolutions in a Hexapod carpet wear testing apparatus. The 8000 revolutions ca be taken as representing approximately 4-5 years normal wear in actual use.

Analyses of the carpets before and after .wear showed no change in permethrin content indicating a treatment which is fast to wear.

Instrumental measurements of colour changes produced by talc application at the 2% level on commercial carpets of various colours showed zero or negligible change even on dark colours.

Example 3

Permethrin was applied to a fine polyester powder by solvent rotary evaporation as described in Example 1. The powder was a steam fusible type with a melting point of 60°C and particle siz range of 0-80 μm. The powder was treated to a level of 1.25% permethrin. This was then applied to cut pile and loop pile carpet constructions at the level required to achieve a _. treatmen of about 0.22% permethrin owf. The powder was sprinkled onto th sample then brushed in to distribute the powder more evenly through the pile. The carpet samples were then steamed for time ranging from 15 sees to 3 minutes. Representative samples were submitted for bioassaying >i ^* .h T.bisselliella according to the protocol outlined in IWS TM26. Of the cut pile samples tested, sample A which had been steamed for 3 mins and had a resultant treatment level of 0.014% on pile weight resulted in 100% mortality with 0% mortality in the control. Sample D which had been steamed for 15 sees and had a resultant treatment level of 0.013% permethrin on pile weight produced the same result. Powd in which permethrin was incorporated in the polyester polymer me at a level of 1.25% before the grinding/powdering process gave similar results.

Thus by this invention there is provided a method of applyi insect-resist agents to animal fibres or products thereof which overcomes to a significant degree pollution problems inherent in current treatments.

Particular examples of the invention have been described and it is envisaged that improvements and modifications can take plac without departing from the scope of the appended claims.