WO2001073188A1

WO2001073188A1 - Disposable cleaning cloth

Info

Publication number: WO2001073188A1
Application number: PCT/EP2001/003315
Authority: WO
Inventors: Christian Quellet; John Christoph Soper; Sandrine Dumas; Elisabeth Rinaudo
Original assignee: Givaudan Sa
Priority date: 2000-03-27
Filing date: 2001-03-23
Publication date: 2001-10-04
Also published as: AU2001252231A1

Abstract

The invention is related to a disposable cleaning cloth consisting of a fibrous woven or non-woven tissue having fixed on its surface microcapsules containing at least an odoriferous liquid active ingredient, whereby the microcapsules provide a long-lasting active ingredient release in the air and burst-like active transfer of perfume when a surface of a solid material is wiped without imparting a fatty or oily aspect to the surface. The fixation of the microcapsules is performed mechanically and/or electrostatically and/or by an olfactory neutral adhesive.

Description

Disposable cleaning Cloth

The invention is related to a disposable cleaning cloth consisting of a fibrous tissue which might be made of woven or non-woven material.

Recent developments of cleaning clothes, especially of dry cleaning clothes, show that new solutions of problems in the field of release technologies of active agents are needed. The patent publications US 5525397 and JP 98- 152815 describe dry cleaning clothes. Usually an active liquid is applied directly on the tissue by coating, spraying or by mixing with an impregnating fluid. However, when at least one active agent is volatile and particularly when it is an organoleptic compound or composition unwanted effects occur. Firstly, a high amount of active agent is required to impart enough activity over the life time of the cloth. Secondly, the release of the active agent is not properly controlled and most of the volatile compound or composition is lost within a few days after the first use. As a consequence, the effect of the active agent emanating from fresh clothes when first used may appear too intensive to the user, while it may appear too weak after some days or weeks after the package containing the clothes has been opened. Thirdly, as a high level of active agent must be present on these fresh clothes, handling these clothes will cause an undesired transfer of the active agent to the hands of the user and/or an uncontrolled active agent transfer to the surface to be cleaned, which then might exhibit an undesired oily or dirty aspect.

In the particular, if an active liquid ingredient which is or contains an organoleptic compound or composition - hereafter also called perfume - is used, it is of considerable interest to develop a system that provides a controlled delivery of the perfume from the cleaning clothes such that (i) a long lasting olfactory signal can be perceived on the cloth before use, (ii) an efficient scent boost is produced on a surface to be cleaned with that cloth and (iii) the transfer of the perfume to the cleaned surface is not accompanied with the appearance of a fatty or oily aspect.

In order to fulfill these requirements it is therefore necessary to provide a system that releases slowly the perfume during the whole life of the cleaning cloth such that the scent emanating from the cloth is slight or slow and regular or constant when the cloth is new or not in use and produces a burst-like release of the perfume when the cloth is wiped on a surface of a material which should be cleaned. According to the invention this object is solved by microcapsules fixed on the fibrous tissue the cloth is made of and which tissue might be woven or non- woven. Such microcapsules are defined as dual release microcapsules _; and provide a dual release profile characterized by a long-lasting active release of the perfume in the air and a burst-like active transfer release of the perfume due to an attack of the microcapsules by wiping the surfaces to be cleaned with cloth. The cleaning cloth consists of a woven or a non- woven material, especially selected from the group consisting of polyolefines, polyesters, cellulose and cellulose derivatives. Preferably, these materials are supplied in the form of microfibers. Thus, especially dry clothes retain the dirt mechanically and electrostatically. The dual release microcapsules according to the invention are obtained by a coacervation process of gelatin with gum Arabic and/or carboxy methyl cellulose which process is described in the patent publication WO 99/17871.

The liquid active ingredient according to the invention is an organoleptic compound or composition containing at least one fragrance or a fragrance precursor or an odor masking compound and/or a biologically active compound, e.g. a biocide, insect repellent, antibacterial agent, vitamin (specially for skin cleaning) or a cleaning agent or a surface finishing agent.

The dual release microcapsules according to the invention can be fixed to the cloth mechanically and/or electrostatically and/or by an adhesive. The texture of the cloth may be sufficiently intricate to allow mechanical anchoring and fixation of the microcapsules without the need of an adhesive. Further, the electrostatic charge of the cloth may be sufficiently high to allow irreversible fixation of the microcapsules without the need of an adhesive. Such a high electrostatic charge is for example produced on contacting the fibrous tissue of the cloth with rolls or guides at high speed on converting lines, e.g. as those are used for the manufacturing of cleaning clothes. Combining both the mechanical and electrostatic fixation of microcapsules is preferred.

Thus, the cloth according to the invention can be produced by applying the microcapsules onto the tissue of the cloth having a high electrostatic charge and/or an intricate fibrous structure, which is capable of retaining physically the microcapsules. The retention of the microcapsules is expressed in weight of microcapsules per surface area of the cloth (g/m²) .

In addition, it may be necessary to provide an adhesive that fix the dual release microcapsules on the tissue material of the cloth, whereas the adhesive has to be developed in such a way that it does not significantly affect the texture or touch of the tissue material and that no adhesive is transfered onto the surface of the material to be cleaned. Thus, in order to retain the texture of the cloth and a pleasant touch of the finished cloth, the flexibility of the adhesive must not differ too much from the flexibility of the unfinished cloth, i.e. starting tissue material.

It has surprisingly been found that the procedure of producing microcapsules by the coacervation process of gelatin with gum Arabic and carboxymethylcellulose, as described in the afore mentioned WO 99/17871, provide microcapsules exhibiting the desired dual release mechanism described above. According thereto, the dual release microcapsules are produced in two steps. In a first step, the microcapsules are produced by coacervation of gelatin and gum arabicum on oil droplets and then separated from the coacervation medium and dried by a conventional technique. In a second step, the liquid active ingredient diffuses into the dry microcapsules based on a mechanism which is described in that patent publication. Typically, a mixture is prepared consisting of 20 to 40% of active ingredient (s) , 40 to 70 % microcapsules, 1 to 20% of water and, optionally, 1 to 20% of ethyl alcohol. Sufficient incorporation of the active ingredients is achieved after a time period which varies from a few minutes up to a few hours. According to the cited WO 99/17871, the size of the microcapsules can be controlled by adjusting the mixing speed in the coacervation reactor. Sizes ranging from 20 to some hundreds of micrometers can be obtained with an acceptable monodispersity. Microcapsules most suitable according to the present invention have sizes ranging from 50 to 250 micrometers, preferably 100 to 200 micrometers. Microcapsules that are too small do not break easily under wiping, while microcapsules that are too large will not adhere strongly enough to the cloth.

Alternatively, the microcapsules can be coated with a hydrophobic material to improve the retention of the liquid active under high humidity conditions. Suitable coating materials include waxes, crystalline waxes, fatty acids and their esters, water-insoluble polymers like polyethylene, polyisobutylene, poly(alkyl acrylates) , cellulose derivatives, poly (vinylalcohol-co-vinylalcohol esters) having a degree of hydrolysis lower than 83, polyesters and thermoplastic starches, whereby waxes and cellulose derivatives are preferred.

Fixation of the microcapsules onto the tissue may be achieved with the help of an adhesive consisting of a polymer, a low molecular weight diluent and, optionally, a resin. Preferably, the adhesive is tacky at the temperature where the microcapsules are applied onto the tissue and non-tacky at the temperature of utilization of the cloth. The specific characteristics of adhesives are advantageously be evaluated by inspecting the thermal evolution of their dynamical mechanical properties after bonding by submitting an adhesive layer to an oscillary stress at constant frequency and amplitude, and then the mechanical response of the system is measured as described for example by D.W. Bamborough, Adhesive Age (1988) 11, 40) . Adhesives that match with the requirements of the present invention, possess a dynamic mechanical pattern, as measured at 1Hz, are characterized by:

- a glass temperature ranging from -20°C to +10°C, preferably from -10°C to +10°C and

- the existence of a broad maximum of the loss elastic modulus to store elastic modulus ratio (usually referred to as δ) , expanding between - 40°C and +40° C, and

- a value of the loss elastic modulus, G' ' , not lower than 5 x 10³ and not higher than 10⁶ Pa throughout the temperature range of use

- a value of the store elastic modulus, G' , not higher than 10⁹ and not lower than 10⁸ Pa in the temperature range between Tg - 30°C and Tg.- 20 °C, and

- the existence of four distinct viscoelastic domains , namely:

a) a glassy domain at temperature lower than -15 +/- 5°C, characterized by G' values larger than G' ' , b) a transition domain expanding from - 15 +/- 5°C to + 20 +/- 10°C, where G' is smaller than G' ' , c) a rubbery plateau expanding from 20 +/- 10°C to 85 +/- 5°C, where G' is larger than G' ' , d) a second transition domain expanding from 85 +/- 5°C to 120°C, where G' falls to zero Pa and is smaller than G' ' and where the ratio of G' to G' ' diverges and becomes non measurable.

Furthermore, the adhesive should be olfactory neutral, i.e. should not influence the odoriferous characteristics of the present active ingredient. Adhesives which are susceptible to possess the above characteristics and, therefore, are within the scope of the present invention, are adhesives which are available in form of or based on permanent hot melts, UV- or electron beam curable cold melts, natural rubber dispersions, especially latex, and solutions, synthetic rubber, especially poly-isoprene, and dispersions and solutions, and waterbone acrylic dispersions and solutions. Preferred adhesives are permanent hot melt adhesives and aqueous synthetic rubber dispersions.

Hot melt adhesives of particular interest according to the present invention are mixtures containing at least one polymer and, optionally, a low molecular weight diluent and a resin. The polymer is typically selected from the group consisting of polyisobutene, polybutylene, polyisoprene, polyisoprene-b-polystyrene diblock and triblock copolymers, whereby polyisobutene is particularly suitable. The low molecular weight diluent can be a liquid or a wax. Preferred diluents are mineral oils, paraffines, hydrocarbon waxes and/or organosilicones . The resin is typically a hydrogenated hydrocarbon resin.

According to the invention synthetic rubber dispersions can be used solely or in combination with a resin. Adhesives belonging to the above mentioned group are characterized by the existence of a tacky state and a non- tacky state. The tacky state is produced at that temperature or within that time interval, where the loss to store modulus ratio passes through a maximum. In case the adhesive is a permanent hotmelt, this state is above the glass temperature Tg of the adhesive, specifically 10°C or more above Tg and below the melting temperature T , more spacifically about 10°C below Tm. In the case of dispersion and solution adhesives the tacky state starts during the drying process of the adhesive and ends when the adhesive is completely dried. For UV- or EB-curable adhesives, the parameter controlling the appearance and disappearance of the tacky state is the degree of crosslinking, which is directly proportional to the cumulative radiation intensity received by the adhesive.

The optimum adhesive profile of adhesive formulation can easily be achieved by carefully adjusting the respective amounts of polymer, diluent and, optionally, resin, and the thickness of the adhesive layer.

The cloth according to the invention can also be produced by the fixation of the microcapsules on the tissue which involves applying the adhesive onto the tissue when the adhesive is tacky, applying the microcapsules onto the adhesive and quenching the system down to the non-tacky state by cooling or drying. Thereby the application of the adhesive is preferably performed with a static or rotating nozzle, an enduction cylinder or a broad spray unit. Optionally, an adhesive pattern is created by using e.g. a structured cylinder. Microcapsules are applied by spraying or using a vibrating dispenser, but preferably the microcapsules are applied using a spray. Once the non- tacky state of the adhesive has been reached, the free microcapsules are removed from the surface by pneumatic suction, mechanical sweep or vibration and recycled in the application loop.

Alternatively, the adhesive can be coated directly onto the microcapsules under non-tacking conditions using spray-coating or tumble mixing. The coated microcapsules are then applied to the cloth at a temperature avove the onset of the tacky regime.

The microcapsules can be colored with a non-transferable dye and can be applied onto the surface of the tissue according to a pre-defined pattern like commercial logos, writing or any other decorative patterns.

The perfumed cloth according to the present invention can be used for cleaning any material having a solid surface without undesirable adhesive transfer to the surface.

Optionally, the perfumed cloth according to the present invention can further be impregnated with a liquid cleaning or finishing composition.

Example

A) Fabrication of perfumed microcapsules

Perfume free microcapsules were prepared in a coacervation reacto mixer by coacervation of gelatin with gum arabicum on oil droplets using the procedure disclosed in patent publication W099/17871. Miglyol Neutral Oil, 250 bloom type A gelatin, and gum Arabic FCC powder SP Dri were used as raw materials. A microcapsule size distribution ranging from 100 to 150 micrometers was obtained by carefully selecting the speed and geometry of the coacervation reactor mixer. Then the microcapsules were dried in a vacuum oven dryer at about 80°C or in a fluid bed dryer at about 70°C to yield a free-flowing powder consisting of an oil droplet surrounded by a layer of gelatin-gum complex. The free-flowing, dry gelatin-encapsulated perfume compound was obtained by mixing 55% dry microcapsules with 40% perfume and 5 % water. The optimal absorption time of the perfumed liquid phase was between about 1 hour and 10 hours, depending upon the partition coefficient of the particular perfume compound. As a consequence of the absorption process, the microcapsules swelled and reached the desired size distribution of between 150 to 200 micrometers.

B) Preparation of adhesive solutions

The four adhesive solutions as summarized in Table I were obtained by mixing polyisobutene polymers, paraffin oil, silicone fluid and/or fully hydrogenated hydrocarbon resins with or without solvent.

Table I

0 . 5% 0 . 5% 99%

99% 11 915-

* delivered by BASF ** delivered by Hercules *** delivered by

Witco

C) Application of the microcapsules on the tissue.

A dry tissue consisting of a non-woven polyolefinic microfibers reinforced with a paraffin coating is used as model yielding three samples I, II, III having a surface area on each side of 588 cm².

Sample I is perfumed by spraying 300 mg/588 cm² of an alcoholic perfume composition and then allowed to dry at room temperature. Sample B is perfumed by spraying 200 mg perfumed microcapsules as obtained from the procedure described in paragraph A, whereby the perfume quantity applied being the same as applied on Sample I. 80mg of perfumed microcapsules remained on the tissue after shaking. Sample III is coated by spraying the adhesive solution b of Table I in an amount of 0,08g/588 cm² and then perfumed with 200mg perfumed microcapsules as obtained from the procedure described in paragraph A, the perfume quantity applied is the same as applied on Sample I. An amount of 160mg microcapsules remained on the tissue.

The microcapsules were sprayed each on one side of the so prepared clothes. The clothes were then brought in contact with the surface of a ceramic material to be cleaned. Samples I, II and III were compared in terms of scent intensity before, during and after use, as well as in perfume transfer capability to solid surfaces of the material to be cleaned. The performances of the clothes in delivering a fresh and powerful scent during wiping on the solid surfaces were each evaluated in an closed chamber having a volume of 2m³ coated with ceramic files. Each chamber is treated with one of the above perfumed clothes. In the first experiment the plates are wiped with freshly prepared Sample I. In the second experiment the freshly prepared Sample II and in the third example freshly prepared Sample III was used.

Olfactory evaluations after wiping the surface of the tiles were made after 5 min, 120 min and 180 min. The results of these olfactory evaluations show the intensity of perfume delivered from each Sample after use.

Table II

The experiments were repeated with aged clothes after one month storage at room temperature in open packages. Only Sample III gave an odoriferous impression and still a strong odor when the cloth was used in the same kind as in the just above described three experiments.

While the invention has been illustrated and described with respect to illustrative embodiments and modes of practice, it will be apparent to those skilled in the art that various modifications and improvements may be made without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited by the illustrative embodiments and modes of practice.

Claims

1) A disposable cleaning cloth consisting of a fibrous woven or non-woven tissue having fixed on its surface microcapsules containing at least an odoriferous liquid active ingredient, whereby the microcapsules provide a long-lasting active ingredient release in the air and burst-like active transfer of perfume when a surface of a solid material is wiped, thereby not imparting a fatty or oily aspect to the surface.

2) The cloth of claim 1, characterized in that the microcapsules are fixed mechanically and/or electrostatically.

3) The cloth of claim 2, characterized in that the microcapsules are additionally fixed by an olfactory neutral adhesive.

4) The cloth according to claim 3, characterized in that the tissue consists of a material selected from the group consisting of polyolefines, polyesters, cellulose and cellulose derivatives.

5) The cloth according to claim 1 or 4, characterized in that the microcapsules are obtained by a coacervation process known per se.

6) The cloth according to any one of the claims 1 to 5, characterized in that the liquid active ingredient contains at least a fragrance, a fragrance precursor, an odor masking compound and/or a biologically active compound.

7) The cloth according to any one of the claims 3 to 6, characterized in that the adhesive consists of a polymer, a low molecular weight diluent and, optionally, a resin. 8) The cloth according to any one of the claims 3 to 7, characterized in that the adhesive is tacky at a temperature where the microcapsules are applied onto the tissue and its flexibility is in the range of the tissue at the temperature of utilization.

9) The cloth according to any one of the claims 3 to 8, characterized in that the adhesive is selected from or based on at least one component selected from the group consisting of a permanent hot melt, UV- or electron beam curable cold melt, natural rubber dispersion and solution, synthetic rubber dispersion and solution, and waterbone acrylic dispersion and solution, preferably a permanent hot melt or an aqueous synthetic rubber dispersion.

10) The cloth of claim 9, characterized in that the adhesive is a latex.

11) The cloth of claim 9, characterized in that the adhesive is selected from the group consisting of poly- isoprene, polystyrene-polyisoprene diblock and triblock copolymers . 12) The cloth of any one of the claims 7 to 11, whereby the adhesive is characterized by

a glass temperature ranging from -20°C to +10°C, preferably from -10°C to +10°C and

- a value of the loss elastic modulus, G' ' , not lower than 5 x 10³ and not higher than 10⁶ Pa throughout the temperature range of use, and - a value of the store elastic modulus, G' , not higher than 10⁹ and not lower than 10⁸ Pa in the temperature range between Tg - 30°C and Tg.- 20 °C, and

- the existence of four distinct viscoelastic domains , namely:

a) a glassy domain at temperature lower than -15 +/- 5°C, characterized by G' values larger than G' ' , b) a transition domain expanding from - 15 +/- 5°C to + 20 +/- 10°C, where G' is smaller than G" , c) a rubbery plateau expanding from 20 +/- 10 °C to 85 +/- 5°C, where G' is larger than G' ' , d) a second transition domain expanding from 85 +/- 5°C to 120 °C, where G' falls to zero Pa and is smaller than G' ' and where the ratio of G' to G' ' diverges and becomes non measurable.

13) The cloth according to any one of the claims 1 to 12, characterized in that the size of the microcapsules is from 50 to 250 micrometers, preferably fromlOO to 150 micrometers .

14) The cloth according to any one of the claims 1 to 13, characterized in that the microcapsules are coated with a material selected from the group consisting of waxes, especially crystalline waxes, fatty acids and their esters, water-insoluble polymers, especially polyethylene, polyisobutene, poly(alkyl acrylates) , cellulose derivatives, poly (vinylalcohol-co-vinylalcohol esters) having a degree of hydrolysis lower than 83, polyesters and thermoplastic starches.