GB2507750A

GB2507750A - Fabric softener with colloidal silica for imparting stain resistant properties

Info

Publication number: GB2507750A
Application number: GB201220083A
Authority: GB
Inventors: George Costa; Tony Wilson
Original assignee: Intelligent Fabric Technologies PLC
Current assignee: Intelligent Fabric Technologies PLC
Priority date: 2012-11-07
Filing date: 2012-11-07
Publication date: 2014-05-14
Also published as: GB201220083D0

Abstract

A fabric conditioner comprises a carrier or bulking agent, at least one surfactant, and a hydrophilic material. The hydrophilic material is preferably colloidal silica, which may be present from 0.01 to 2%wt., and may form a hydrophilic coating that helps to repel hydrophobic dirt from the surface of the fabric. A suspension or lubricating agent, such as paraffin wax may be included. The at least one surfactant may be a quaternary ammonium salt. The composition may also comprise a viscosity modifier, at least one preservative, and a perfume. The carrier may be a liquid solvent, such as water or a mixture of water and an alcohol, such as isopropanol. The carrier may be a bulking agent in dry powder form, and further comprising at least one processing aid, such as a polyoxyalkylene compound.

Description

Fabric Conditioner This invention relates to a fabric conditioner that contains an additive capable of providing a fabric or textile with a protective coating, to impart stain resistant properties to the fabric.

It has become common in the consumer and residential sector to use fabric softening compositions that include surfactants and minor quantities of optional ingredients such as perfumes, stabilisers, preservatives and colorants. The softeners are usually conveniently added to a washing machine in liquid form.

Fabric softeners contain surfactants which have lubricant properties and are electricaHy conductive. The surfactants prevent static electricity and make the fabrics feel smoother.

In addition, the softener compositions often provide a thin coating on the fabric fibres to make the fabric fluffier, softer and better smelling.

There are two main types of fabric softener; those that use cationic surfactants and those that use anionic surfactants. The choice of softener can vary depending on the fabric to be treated. Some softeners are more suitable for cellulose-based fibres, whilst others have a higher affinity to hydrophobic materials such as nylon, polyethylene terephthalate, polyacrylonitrile, etc. Softener compositions are usually prepared as an emulsion, as the surfactants are frequently hydrophobic.

The lubricating properties of the cationic softeners are due to the positive charges of the surfactants within the softener composition. Surfactants are usually acidic and the positively charged particles of the surfactant attract the negatively charged particles within the fabric.

The negative charge of the fabric is neutralized, creating a lower frictional resistance. This reduces the static cling and the fabric feels softer to touch. The molecules of these surfaetants tend to have long aliphatie chains which are oriented towards the outside of the fibre, providing lubrication. As cationic surfactants can impact the water adsorption properties of the fabric, they are often combined with other chemicals with lower affinity to the fibres.

Many commercial fabric softeners are based on quatemary ammonium salts with one or two long alkyl chains, for example, dipalmitoylethyl hydroxyethylmonium methosulfate. Other cationic compounds can be derived from imidazolium, substituted amine salts, or quatemary ailcoxy ammonium salts. Early formulations commonly used dihydrogenated tallow dimethyl ammonium chloride (DHTDMAC). Fabric softeners containing quatemary ammonium salts operate well in conventional residential wash and dryer cycles and provide softness to textiles that are both woven and non-woven.

Cationic surfactants arc incompatible with the anionic surfactants used in detergents, with which they tend to form a solid precipitate. Therefore, they have to be added during a separate cycle, typically the rinse cycle of a conventional domestic washing machine. In contrast, anionic softeners can be directly combined with anionic surfactants. Examples of anionic surfactants and antistatic agents arc salts of monocsters and diestcrs of phosphoric acid and the fatty alcohols. They can also be combined with more conventional cationic softeners. This has led to the development of two-in-one formulations, where the fabric softener is combined with thc dctergcnt.

A further development is the ability to add a fabric conditioner to fabrics in a tumble dryer.

Fabric softener is applied to a flexible substrate that carries the fabric softener and is added to the drying cycle. The advantages of this method of conditioning the fabric include avoiding a separate wash cycle for the addition of a fabric softener, and avoiding any undesired interactions of the softening agents with detergents.

Using conventional domestic laundering processes it can often be very difficult to rcmovc stains, oily material or soiling from textiles. In addition, even if the stains or unwanted materials have been removed from the fabric and a now fairly clean textile material is being washed, soil remaining in the wash water can be re-deposited onto the textile item (or onto other fabric items in the water) prior to the end of the wash cycle. This can lead to premature aging of fabric items, and effects such as greying/yellowing can occur due to the deposition of unwanted materials onto the fabric. In this manner, textiles that are frequently washed rarely maintain a truly clean appearance.

Coating compositions and treatment methods are available that can be applied to selected consumer articles to repel dirt, moisture, or to preserve the appearance of such articles. For example, products are available that claim to improve the water repellent properties of fabrics. These coatings are particularly useful for fabric based footwear, outerwear and upholstery, for example. These products are typically available as an aerosol for consumer application. Examples of this type of product include Seotchguard® brand products, RivivexiM and Nilcwax TXM. Although these products are very useful, the coatings usually contain either siloxanes or fluorochemicals. Concerns have been raised about the use of fluorochemicals as many of these chemicals are persistent in the environment (they tend to bioaeeumulate) and can be toxic. When applied to textiles fluorochemicals tend to make fabrics feel stiffer and harsher. The production of longer chain fluoroehemieals has generally been reduced worldwide due to environmental concerns. Siloxanes do not exhaust well from a conventional laundry cycle, and they tend to require large doses in order to cover the required area.

There are a small number of existing products available that are desied for a wash-in application, but these are directed to restoring the water repellent properties of a factory applied finish. Products include Nikwax TXFM which is designed for the restoration of water-repellent properties and Storm Proofer Plus "Rudolf'TM, which is a stain and abrasion resistant finish based on a water dispersible hydrocarbon.

According to the present invention, there is provided a fabric softener comprising a carrier or bulking agent, at least one surfactant and a hydrophilic material. By way of example, the hydrophilic material may be in the form of colloidal silica. The surfactant can be a quaternary ammonium salt, for example. The fabric softener may take the form of a liquid formulation, or alternatively the liquid formulation may be applied to a suitable substrate for use in a tumble-dryer. It is also possible to formulate the fabric softener composition as a dry powder, for dispersion in a liquid during a conventional wash/rinse cycle.

The invention relates to a fabric conditioner designed protect the fabric against stains and dirt, hclping to keep the fabric in the original condition. The fabric soficner thus providcs the benefits of a protective coating in an easy to use formulation, which can be added to a conventional rinse cycle. The user is able to obtain the benefits of prolonging the life of S their fabrics when laundering in the usual way without any additional inconvenience. The protective coating does not result in a stiffening' effect on the fabric; instead the fabric is softened as it would be if any alternative fabric softener were to be used. It is also important that the water absorbency of the fabric is not affected by the softener.

In addition, the fabric softener imparts a uniform coating to the fabric. Previously, although spray coatings could be evenly applied as a factory finish it would have been both difficult and time consuming for a domestic consumer to achieve a uniform coating. For industrial consumers, providing a protective coating would prcviously have involved additional processing steps, whilst the present inveiltion allows a protective coating to be applied to the fabric during a more convenient rinse cycle.

The preferred example of the fabric softener of the present invention includes a quatemary ammonium salt; a carrier; and a further active ingredient to provide stain resistant properties in the form of a hydrophilic material. The formulation may further comprise one or all of the following; viscosity modifiers, preseivatives and/or perfume.

Particularly preferred forms of the invention include fabric softeners intended for use during the wash cycle or final rinse of a wash cycle in the form of liquids or powders. The terms "fabric conditioner" and "fabric softcncr" should be understood to be intcrchangcablc in the context of this application. The fabric softener can also be applied to a substrate for use ill a dryer, whcre thc fabric softcning propcrties of thc formulation are impartcd to the fabric articles during a drying step. The dryer may be a tumble-type dryer or equivalent. The fabric softener can be used in either residential machines, or in industrial and institutional settings. This includes fabric or textile laundering operations in commercial or service industries, including for example, hotels, hospitals, nursing homes, restaurants, health clubs, prisons, etc., as well as the preparation of fabrics in a factory setting.

As mentioned above, one component of the fabric softener composition is a quaternary ammonium compound. Examples of suitable quatemary ammonium compounds that could be used include alkylated quaternary ammonium compounds, alkoxylated quatemary s ammonium compounds, ring or cyclic quatemary ammonium compounds, aromatic quaternary ammonium compounds, di-quaternary ammonium compounds, amidoamine quaternary ammonium compounds, triethanolamine based esterquats and ester quatemary ammonium compounds. A mixture of one or more of these compounds could also be used.

The quatemary ammonium compounds may use any counter ion that has fabric softening properties. Examples of suitable counter ions include chloride, methyl sulphate, ethyl sulphate and sulphate. Particularly preferred surfactants include di-hydrogenated tallow hydroxyethylmonium methosulphate, dimethyl distearic ammonium chloride, bis(hydrogenated tallow alky dimethylammonium chloride, and dipalmitoylethyl hydroxyethylmonium methosulphate.

The amount of quatemary ammonium component can be in the range of approximately 2% to 30% by weight of the final product. More preferably, the quatemary ammonium content can be from approximately 5% to 20% by weight, from approximately 10% to 15% by weight or most preferably, from 11 to 13% by weight of the final product.

Where the fabric softener is a liquid, the can-icr for the formulation is preferably water. This may be tap water, but is more preferably de-ionised water. Optionally distilled, purified or filtered water can be uscd. The carrier can be formed from a mixture of water and water soluble organic solvents, such as short-chain alcohols. Ethanol, propanol, isopropanol, butanol, benzyl alcohol and mixtures of these solvents can be added to the water in quantities of up to approximately 10% by weight, more preferably up to approximately 5% by weight, of the carrier fluid. Soluble organic solvents such as the alcohols mentioned above are used if it is desirable to increase the concentration of active ingredients in the fabric softener composition whilst still retaining the desired product viscosity.

If a free flowing powder form of the fabric conditioner is required, it may be necessary to USC atomiscd powders of the desired quaternary ammonium compounds. US5,200,097 (Hughes et al) describes the advantages of adding processing aids such as polyoxyalkylene derivatives to quatemary ammonium compounds prior to atomisation. Any suitable bulking S agent or carrier can be used in combination with the atomised quateniary ammonium compounds.

The fabric conditioner may also be provided on a substrate impregnated with the fabric softening ingredients, for usc in a drying cycle. The substrate can bc a sponge, cloth (woven!knitted or foil-woven), a porous sheet, paper or any other suitable vehicle for carrying the fabric softener. Preferably, the substrate will have an open or porous structure, and good absorbent properties. The amount of conditioning composition affixed to the flexibic substratc may vary dcpcnding on the sizc of the substrate and the dCgrCc of fabric conditioning desired. The fabric conditioner is preferably applied in liquid form to the substrate, and this is commonly achieved by processes such as dippiilg or spraying.

FoHowing the application of the liquid fabric softener, the substrates are dried to evaporate any residual solvents (e.g. water).

The fabric softener composition may further comprise colloidal silica. Typically the particles of colloidal silica are fine amorphous and non-porous particles, which are usually spherical or near-spherical. The silica particles in colloidal silica dispersions have fully hydroxylated surfaces and are very hydrophilic due to the high number of surface hydroxyl-silanol groups. When these particles are applied to the fabric, they settle in the crevices of the fibre's surface and in-between the rough fibre filamdilts to form a hydrophilic coating.

This helps to repel hydrophobic dirt from the surface of the fabric, preventing dirt from adhcring to the fabric. Simple clcaning becomcs more cffectivc as dirt rinscs away more easily from the surface of the fabric.

The use of colloidal silica provides the added advantage of imparting anti-wrinkling properties to the fabric. A liquid fabric softener may contain colloidal silica in quantities ranging from O.Olwt% to lwt% of the final product, for example; more preferably from O.O5wt% to O.5wt%. Specific examples of the liquid fabric softener have been created with a concentration of between 0. lwt% and 0.2wt% colloidal silica as a percentage of the liquid fabric softener product, and with between O.l5wt% and O.2wt% colloidal silica. The percentage by weight of colloidal silica in the final product is higher if the final product is a powder or a dry substrate impregnated with softener.

To improve the dispersion of the colloidal silica a lubricating agent, a suspension agent or surfactant can be used. One example of a suitable lubricating agent is paraffin wax. The paraffin wax may also have the additional effect of reducing the agglomeration of the colloidal silica particles. A liquid fabric softener composition may contain between 0.OOlwt% and 0.lwt% paraffin wax, more preferably between 0.Olwt% and 0.O5wt% paraffin wax as a percentage of the final product.

When applied to the fabric as part of the fabric softener composition, the colloidal silica particles provide a protective coating to the fibres of the fabric, repelling dirt and oils. The purpose of the coating is to reduce or minimise the ingress of any stains or dirt that the fabric is exposed to. Due to the method of application, the coating is relatively uniform compared with the coating achieved by spray-coating. The colloidal silica particles are replenished with every application, for example, every time the article is washed.

For liquid formulations, viscosity modifiers or control agents can be used to reduce the viscosity of the formulation, in order to produce a pourable formulation with a viscosity that is acceptable to the consumer. Examples of viscosity modifiers include fatty acids and cstcrs, watcr-rnisciblc solvents and watcr-solublc ionisablc salts. Watcr-solublc calcium salts are particularly suitable for use as viscosity modifiers. Calcium chloride is one preferred example of a calcium salt suitable for use as a viscosity modifier, although alternatives such as magnesium chloride, sodium chloride, potassium bromide and lithium chloride can also be used. Jonisable salts also have the added advantage that they can often improve the performance of the surfactant. Relatively low concentrations tend to be required. Viscosity agents can be present in liquid formulations in quantities of between O.OOlwt% and lwt%, more preferably between 0.Olwt% and O.5wt%, and most preferably in the range ofO.Olwt% and 0.lwt%.

The formulation may also include preservatives, anti-static agents, odour capturing agents and perfumes. Perfumes may be formed from natura' or synthetic ingredients.

Stabilisers or preservatives are used to improve the shelf-life of fabric softeners. For fabric softeners in liquid form, the stabilisers ensure the stability of the emulsion during storage, cvcn at variable temperatures. Stabilising agents may include antioxidants, such as ascorbic acid, propyl gallate and citric acid and reductive agents, such as sodium borohydride and hypophophorous acid. Preservatives can include anti-microbial agents such as isothiazolinone-based chemicals (in particular isothiazol-3-one biocides) or glutaraldehyde-based products. As a guide, preservatives can be present in a liquid formulation in quantities of up to about 0.3%, more preferably less than 0.2%. The fabric softener composition may contain a mix of two or more stabilising agents and/or preservatives.

Whether a fabric is soft is a quality perceived by users through their tactile senses. Such tactile perceivable softness may be characterised by, but not limited to resilience, flexibility, fluffiness, slipperiness, pliability and smoothness, as well as subjective descriptions such "feeling like silk".

By using the present invention the consumer can protect a fabric item easily by using a conventional washing machine or tumble dryer. The fabric softener of the present invention coats the fabric with a compound that provides resistance against stains and dirt. This can prolong the life of the fabric item, and helps to maintain the original appearance of the item.

The present invention provides the added advantage of applying a uniform protective coating to fabric without the use of environmentally harmful fluorochemicals, which adversely affect fabric softness and hand-feel. Many quatemary ammonium compounds, particularly those with ester linkages in the aliphatic chains, have demonstrated improved biodegradation kinetics, lowering the environmental bioaccumulation levels.

It will be recognised by a person skilled in the art that numerous formulations can be produccd according to the invcntion. Non-limiting cxamplcs of suitablc formulations arc provided below.

Example 1

A first example of a liquid fabric softener composition: Chemical Name %wt in final product Function Water To 100% Carrier (solvent) di-hydrogenated tallow 10-15 Cationic surfactant hydroxycthylmonium methosulphate (Esterquat) Calcium chloridc 0.001 -0.2 Viscosity modifier 5-chloro-methyl-2H-0.02 -0.1 Preservative isothiazol-3-one 2-mcthyl-2H-isothiazol-3-0.001 -0.005 Prcscrvativc one Fragrance 0.1 -1.5 Perfume Colloidal silica 0.01 -0.5 Stain repellent Paraffin wax 0.001 -0.05 Lubricant

Example 2

A sccond, fragrancc-frcc, conccntratcd, cxamplc of a liquid fabric softcncr composition: Chemical Name Vowt in final product Function Watcr To 100% Carricr (solvent) Tsopropanol 5 -10 Carricr (solvcnt) bis(hydrogenated tallow 10-20 Cationic surfactant alkyl) dimethylammonium chloride Calcium chloride 0.02 -0.4 Viscosity modifier 5-chloro-2-mcthyl-4-0.1 -0.2 Prcscrvativc isothiazolin-3-one Fragrance 0 Perfume Colloidal silica 0.02 -1 Stain repellent Paraffin wax 0.002 -0.1 Lubricant

Example 3

S An examplc of a fabric softener composition in powdcr form: Chemical Name Vowt in final product Function Di-hydrogenated tallow To 100% Cationic surfactant hydroxyethylmonium methosulphate Ethylene oxidc S -40 Processing aid Glycerol mono coeoate 2-10 Processing aid Fragrance 0.5 -2 Perfume Colloidal silica 0.05 -2 Stain rcpcllcnt Paraffin wax 0.002 -0.5 Lubricant The ethylene oxide and glycerol mono cocoate can be melted with the di-hydrogenated tallow hydroxycthylmonium mcthosulphatc and atomiscd to producc a free-flowing powdcr.

Conventional proccsscs can bc used to form thc powdcr, including spray drying, spray congealing and prilling/spray-cooling. The colloidal silica can be added to the molten mixture pilot to atomisation, or can be added to the dry powder pmduct. If the colloidal silica is added to and blended with the dry atomised product, the particle size of the colloidal silica becomes an important ftctor as it affects the homogeneity of the blend.

Claims

Claims 1) A fabric softener composition comprising a carrier or bulking agent, at least one surfactant, and a hydrophilic material.
2) The fabric softener composition according to Claim I, where the hydrophilic material is colloidal silica.
3) The fabric softener composition according to Claim 2, comprising between from 0.Olwt% to 2wt% colloidal silica.
4) The fabric softener composition according to any preceding claim, further comprising at least one of a suspension agent or lubricating agent.
5) The fabric softener composition according to Claim 4, where the suspension agent or lubricating agent is paraffin wax.
6) The fabric softener composition according to Claim 5, comprising between 0.00 lwt% and O.Swt% paraffin wax.
7) The fabric softener composition according to any preceding claim, where the at least one surfactant is a quaternary ammonium salt.
8) The fabric softcncr composition according to Claim?, comprising bctwccn 2wt% and 4Owt% of a quaternary ammonium salt.
9) The fabric softener composition according to any preceding claim, further comprising at least one viscosity modifier.
10) The fabric softener composition according to any preceding claim, further comprising at least one preservative.
11) The fabric softener composition according to any preceding claim, further comprising at least one perfume.
12) The fabric softener composition according to any preceding claim, where the carrier is a liquid solvent.
13) The fabric softener composition according to any preceding claim, where the carrier comprises water, or is a mixture of water and an alcohol.
14) A substrate impregnated with the fabric softener composition of any preceding claim.
15) The fabric softener composition according to any one of Claims 1-11, where the carrier is bulking agent in dry powder form, further comprising at least one processing aid.
16) The fabric softener composition according to Claim 15, where at least one pmccssing aid is a polyoxyalkylene compound.