The method comprises microencapsulation of an active ingredient in microcapsules and putting in contact said ingredient with the clothes including microcapsules in the washing water when washing and delivering the active ingredient through the wall of the microcapsules providing a gradual release of active ingredient particles as a result of the rupture of rubbed microcapsules while the clothes are being used wherein succinic acid is blended with the microcapsules to adhere them to the clothes, then the clothes with microcapsules are submitted to a thermal treatment.
A composition is obtained by blending together microencapsulated active ingredient and succinic acid as a binder agent.
The present invention relates in general in a first aspect, to a method to infuse an active ingredient into textiles by means of microencapsulation, and in particular, to a method to infuse fragrances into clothes.
A second aspect of the invention relates to a composition containing a microencapsulated active ingredient (such a fragrance) prepared for gradual release of the active ingredient on laundered clothes either in a washing machine or in hand washing.
The invention also proposes the use of a binder agent for applying microcapsules containing an active ingredient on laundry either in a washing machine or in hand washing.
There is a market demand for detergents or similar products with additives to wash laundry and infuse it with an attractive and persisting fragrance. The perfume-based additives make washed garments more appealing to the consumer. For instance, it is desired to have a product that could add a subtle fragrance to their clothes with a long-lasting and stable effect: scented detergents that can remain on washed fabrics.
There are currently numerous formulas with value-added functions for the care and treatment of clothes, some of them with perfumes.
Different techniques have been developed to hinder or delay the release of aroma, making it possible for the textile to retain the perfume, but to date few products and procedures can provide long-term release of perfume after prolonged storage.
In addition, there is on-going search for methods and compositions that can effectively and efficiently provide aromas to textile articles during a washing bath. As it can be seen from the following descriptions, various methods of perfume supply have been developed, involving perfume protection during the wash cycles.
Industry efforts concentrate on three main research lines: finding the right formula of a washing product that will keep for longer storage times without significant loss of perfume properties; odour intensity or fragrance level supplied; and the duration of the perfume on the surface of the treated fabric.
Another problem found in the manufacturing of perfumed washing products is the odour intensity, particularly on granular detergent compositions of high density. When density and concentration levels of a detergent are increased, the smell of the perfumed components may become undesirable due to its intensity.
The most extended microcapsules applied to textiles are based on non reactive shells. In order to improve durability to washing or handle some auxiliary products are required to join microcapsules to the fibre surface, see
It is necessary to offer an alternative to the state of the art which covers the gaps found therein, particularly related to the lack of proposals that consider the effectivity of binding agents used when scented microcapsules are applied in a washing machine while laundry, as well as binding effect and its impact in the number of laundry cycles the microcapsules remain on the fabric considering laundry behaviour.
For this purpose the invention develops a method to infuse an active ingredient into textiles by means of microencapsulation, and in particular, to a method to infuse fragrances into clothes.
The invention also proposes a composition formed by scented microcapsules and a binder agent, suitable for household washing machines, that reloads microcapsules on textiles. The perfume durability linked to several textile compositions are also determined, as well as its effectiveness depending on the final use of the garment.
The composition is used while laundering, so that the microcapsules are introduced into fabric yarns. The resulting laundered textiles can be used as normal and the active ingredient will be released gradually from friction in everyday use of the garment.
The method of the invention is intended for gradual release of an active ingredient (such as a fragrance or scented material) on laundered cloths either in a washing machine or by hand washing comprising as already known in the art:
According to the proposal of this invention succinic acid as a binder agent has been added blended with the microcapsules to bond the microcapsules to the clothes and then said clothes with microcapsules are submitted to a thermal treatment in order to provide a suitable curing of the binder agent.
In a suitable embodiment thermal treatment of the binder agent comprises curing it at about 150ºC by ironing the clothes. Curing can be provided alternatively with tumble dryer.
The active ingredient is selected among a fragrance, an anti-bacterial, an anti-mosquito, a moisturizer or a blend thereof.
The microencapsulation is carried on by an interfacial polymerization process (well know in the art) obtaining microcapsules with a membrane is formed using two monomers by preparing a pre-condensed using melamine and formaldehyde in aqueous phase.
As know in the art the wall of the microcapsule is a membrane allowing evaporation through it of said active ingredient.
According to an embodiment the size of said membrane ranges from 0.5 to 150 nanomicrometres.
The composition of the invention to infuse an active ingredient into cloths has been prepared to be used in domestic laundry either in a washing machine or in hand washing for gradual release of the active ingredient on laundered cloths and comprises microcapsules containing said active ingredient (selected among a fragrance, an anti-bacterial, an anti-mosquito, a cosmetic, a lavender oil or blend thereof) and a binder agent to adhere said microcapsules to the cloth fibres , so that said active ingredient is gradually delivered to the cloths trough the capsule wall, the composition comprising a microencapsulated active ingredient and succinic acid as a binder agent blended together.
In order that the resulting effect on clothes will endure prolonged washing and wear the binder agent should be cured at about 150ºC for example by ironing.
According to an embodiment of the invention the microcapsules have a size between 2 to 20 microns.
In an alternative embodiment the microcapsules have a size between 3-8 microns.
The invention also teaches the use of succinic acid as a binder agent for microcapsules containing an active ingredient for applying said microcapsules on laundered cloths either in a washing machine or by hand washing.
The previous and other advantages and features will be more fully understood from the following detailed description of embodiments, with reference to the attached drawings, which must be considered in an illustrative and non-limiting manner, in which:
The present invention shows that scented perfume microcapsules developed by interfacial polymerization with an average size of 8 microns blended together with a binder agent are capable to bond to the textile surface and may last for several washes, releasing the microencapsulated fragrance gradually.
Embodiments of the invention solve the problem of fragrance durability on clothes by creating a microencapsulated product that can be incorporated in domestic washing machines, making it possible for customers to recharge them for prolonging the fragrance or functional effects.
This invention is the result of a search directed to found a suitable binder agent for microcapsules containing an active ingredient for applying said microcapsules on laundered cloths either in a washing machine or by hand washing, providing a good adhesion and permanence of the microcapsules bonded to the fibres when they are pasted onto the fabric while clothes are washed and resisting a high number of laundry cycles with the microcapsules remaining on the fabric.
To this aim the effectiveness of different resins and bonding agents was evaluated in order to find the optimal formula in both composition and concentration of the binder agent, so that the resulting effect on clothes will endure prolonged washing and wear.
Firstly laundry behaviour and lately, change in colour was appraised to determine if the procedure has secondary effects as yellowing.
Microcapsules (CENTER FINISH 164/02 LAVANDA) were supplied by COLOR CENTER (Tarrasa, Spain). The wall material was melamine formaldehyde, and the microcapsules contained lavender fragrance. No further information was supplied by the provider. In order to bond the microcapsules to the fabric, an acrylic resin was applied, also supplied by Color Center and two policarboxilic acids, butanetetracarboxilic acid (BTCA) from Alfa Aesar and Succinic acid (SUC) from Panreac.
The fabric used was a 100% cotton twill fabric with 210 g/m2, which had been chemically bleached with peroxide in an industrial process.
The equipment used to apply microcaspules was a domestic washing machine. Its capacity was 5 Kg and its maximum volume of water was 11 L.
Microcapsules dispersion was made in a glass vessel. Four tests were conducted. Different samples were prepared depending on the binder nature. All the samples contained 5% owf (over weight of fibre) of microcapsules. One of the baths was comprised of microcapsules only. The recipe for samples with polycarboxilic acids (BTCA and SUC) as binder was formulated with 5% owf of microcapsules 4% owf of binder and 2% owf of catalyst. The test with acrylic binder (RES) was based on 5% owf of microcapsules and 12,5 % owf of binder. As soon as the washing machine finished, the fabrics were dried in an IR dryer at 100º C until the fabric was completely dry. Lately, fabrics should be thermally treated so as to polymerize the binder. Commercial brands suggest different temperatures but in this study the curing temperature has been selected in order to get the minimum yellowness on the cotton fibre and different curing temperatures have been evaluated.
Table 1 summarises the treatment conditions herein studied.
For surface observation, a scanning electron microscope (SEM) Phenom microscope (FEI Company) was used. Each sample was fixed on a standard sample holder and sputter coated with a gold -platinum mixture. Samples were then examined with suitable accelerating voltage and magnification.
To test the effectiveness of the binders some laundering tests were conducted. The specimens were treated on a short time program in a Heraeus Linitest for 45 min at 30 °C, in accordance with ISO Standard 105 C01. When a cycle was finished, samples were dried on a horizontal surface. All samples were examined after 1, 2, 3, 4 and 5 cycles.
The particle size distribution of the microcapsules was measured by a Coulter® Counter apparatus (Multisizer Z2, Coulter Electronics, Northwell, UK). The particle size was expressed as the equivalent volume diameter and two replicates were performed for each batch of microcapsule, to reduce error an average curve was calculated and analysed.
This method was used to measure the microcapsules dispersion just immediately it was prepared and the wastewater from the washing machine. The number of microcapsules remaining on the fabric was calculated as the difference between the number of microcapsules on the prepared bath and the number of microcapsules in wastewater.
Furthermore, the wastewater from ISO laundry was also measured to observe the microcapsules behaviour in each laundry cycle.
Some samples were ironed at different temperatures (110, 150 and 200º C). The ironing procedure was performed as UNE EN ISO 105 X11 standard indicated.
Polycarboxilic acids should be cured at temperatures from 150º C in order to induce crosslinking. Knowing that thermal treatment on cellulosic fibres is responsible of yellowness, different curing temperatures have been evaluated.
When microcapsules dispersion was added on washing machine it could be observed that all the samples showed some microcapsules on its surface, including the ones from test one (M25) where no binder was used. images show not sensible differences between the samples obtained with different binder. Thus, only one fabric is shown in
In order to observe the binder effect images from washed samples were analysed as standard ISO 105 C10 indicates. When
Despite the fact that results from SEM can be obvious, the analysis from wastewater can clarify those results as it is more objective and shows the results expressed in the quantity of particles that wastewater contained.
To begin with, the microcapsules deposition on fabric should be characterised. This was calculated as the difference in particles between the number of particles in the dispersion when it was just prepared to be put into the washing machine and the ones in the wastewater after treatment. Moreover, the number of particles in wastewater after each laundry was obtained.
It can be clearly observed a decreasing tendency in the number of microcapsules that remain on the fabric when the number of cycles increases. That behaviour evidences the necessity of any kind of binder if it is desired to increase the microcapsules presence on fabrics. Samples with no binder (25M) do not show any microcapsule between their fibres. This result is in accordance with the ones showed by SEM technique in
In order to determine the influence of the treatment on the fabrics the whiteness index was measured. Table 2 shows either the white index values for each sample and the difference in white compared with the cotton fabric without being treated.
It is interesting to note that microcapsules on fabric (25M) change the whiteness of the original fabric, but if we compare all the measurements slight differences between the different used binders can be appreciated. When measurements are referred to differences (ΔWI CIE) it can be observed than both BTCA-150 and SUC-150 are the ones with higher values. However, in order to evaluate if measured values would be observed by human eye, colorimetric values have been analysed and the difference between each sample and the untreated cotton have been calculated. One of the colour systems on which most chromatic studies are based is the CIE L*a*b*system [a,b]. When we observe chromatic values, we can appreciate that L* value (darkness/lightness) can be considered constant around the value 95. Thus, implies no changes because of the treatment have been induced in fabric lightness. When differences are calculated a clear correlation was found between ΔWI CIE and ΔEa*b*, as it could be predicted. The single most striking observation to emerge from the data comparison is that samples with polycarboxilic acids (BTCA-150 and SUC-150), which include microcapsules show higher witnesses index than cotton treated at the same temperature without microcapsules and no polycarboxilic acids treatments (cotton 150). Colour differences from samples with microcapsules shown in Table 2 demonstrate that despite the fact that espectrofotometer measurements show objective differences, it can be stated that they cannot be appreciated by human eye as they are not higher than 1.
In order to determine if thermal treatment while ironing process would be able to induce crosslinking, samples after being treated in washing machine were ironed at different temperatures value as the Standard establishes. Later on, they were washed as UNE EN ISO 105 suggests so as to check if crosslinking by ironing is effective or not.
It can be clearly observed in
The above proves that a washing machine can be a suitable device to apply microcapsules onto fabrics binder agent.
First of all, the present study compares acrylic resin with two polycarboxilic acids and the thermal treatment to cure the binder agent. It is not surprising that microcapsules remain on fabric surface when the treatment includes some binder as it adheres microcapsules to fibre. It is noticeable that thermal treatment is required if the microcapsule effect should last more than one washing cycle.
As a consequence of thermal treatment, colour changes can be induced on cotton fibre. Chromatic studies have been conducted so as to determine either the thermal influence or the presence of chemicals can produce on fabrics. The evidence from this study suggests that some changes occur, as it was predictable. However, either differences in witness's index or chromatic differences demonstrate they are not sensitive enough to be observed by human eye.
When acrylic resin is compared with polycarboxilic acids and considering thermal conditions for each one, the evidence shows that the later allow microcapsules to remain on the fabric the longer.
From the tests done succinic acid displays the higher number of microcapsules on the fibre. Furthermore, acrylic binder develops some aggregates of microcapsules and makes impossible to test the binder appropriately.
To sum up, when applying microcapsules to fabrics by washing machine, succinic acid if cured at 150º C shows the best results and treated fabric has not changed sensitively the colour. Ironing at 150ºC is effective in the curing process and in the appropriate binding of microcapsules in fabrics.
From the above it has been demonstrated the possibility of applying microcapsules to fabrics in a domestic process using succinic acid in a conventional washing procedure and ironing with a domestic equipment.
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