EP3957710A1

EP3957710A1 - A bacteriostatic concentrate and fabric softener and the use of the concentrate and fabric softener

Info

Publication number: EP3957710A1
Application number: EP20192115.2A
Authority: EP
Inventors: Przemys aw ABUZ; Joanna Macyk; Wojciech Macyk
Original assignee: Anna Twarog Simplyq
Current assignee: Anna Twarog Simplyq
Priority date: 2020-08-21
Filing date: 2020-08-21
Publication date: 2022-02-23

Abstract

The subject of the invention is a concentrate for rinsing fabrics resulting in lasting bacteriostatic, softening and antistatic properties of fabrics, to be used in laundries ensuring ultra-high bacterial purity, in home washing machines and in hospital laundries. The invention also relates to a fabric softener, a concentrate for rinsing and the use of said fabric softener and concentrate for rinsing fabrics.

Description

Field of the invention

The invention relates to a bacteriostatic concentrate for rinsing fabrics, a bacteriostatic fabric softener and the use of said concentrate and fabric softener, in particular in laundries ensuring ultra-high bacterial purity, in home washing machines and in hospital laundries.

Prior art

The prevailing number of textile materials constitutes a mixture of cotton and polyester fibres. Both types of fibres are polymers, wherein cotton consists of over 90% of cellulose and is a natural polymer of plant origin. It is present in the form of long chains of glucose particles connected by oxygen bridges between carbons C-1 and C-4, generated with simultaneous elimination of a water molecule.
Cotton cellulose is characterised by a high degree of polymerisation and tightly packed fibres, usually arranged parallel to each other. Cellulose chains in cotton fibres are maintained in place by means of hydrogen bonds between hydroxy groups of the neighbouring particles. Three hydroxy groups, one primary and two secondary, in each repeating cellobiose unit (a dimer of glucose) are chemically reactive. These groups may undergo substitution reactions, primarily etherification and esterification, and they are used for modifying cellulose fibres, colouring or crosslinking. The second type of fabric - polyester - consists, e.g., of poly(ethylene terephthalate) generated due to a reaction of terephthalic acid with ethylene glycol.
Compared to cotton, polyester is more waterproof, much easier to dry. From a chemical point of view, it is more resistant to the action of acids and bases, as well as numerous organic solvents or typical bleaching agents, compared to cotton. Cotton and polyester are usually used as a mixture of pure cotton and synthetic polyester. Modified in this manner, they form fabrics which are durable and resistant to the action of external and chemical factors. Unfortunately, they are not sufficiently resistant to the action of microorganisms.
Microorganisms living on textiles can be eliminated by aggressive methods of conservation (washing in a temperature of 95°C, ironing/mangling, strong detergents, disinfection); however, after these procedures, a sterilised fabric quickly loses its microbiological purity. Extreme conditions of conservation are not always suitable for all textile products, since they can, e.g., damage many textiles. This is why washing must often proceed under gentler conditions (at a lower temperature, with no bleaching agents).
An agent with an antibacterial effect introduced onto a cloth can delay the colonisation of fabric by microorganisms considerably. Currently, among typical preparations dispensed onto textile materials and resulting in their bactericidal properties, two types of agents are used: biocides (substances fighting microorganisms) and biostatics (substances inhibiting the reproduction of microorganisms). The use of the abovementioned substances in a laundering cycle, at the end of which they are washed away, will not prevent another fast microbiological contamination of fabrics.
The possibility to provide a longer lasting bacteriostatic effect, which is maintained after washing for a period of several washing cycles, is a problem to which a solution is being sought.

Summary of the invention

The abovementioned problem is solved by a concentrate for rinsing fabrics according to the invention, wherein said concentrate for rinsing fabrics can be produced via the following stages:

suspending an emulsifying substance in water in order to produce a suspension,
heating the resulting suspension at a temperature reaching or equal to 80°C under atmospheric pressure along with intense stirring of the suspension in order to produce an emulsion, followed by
adding zinc oxide to the resulting emulsion,

₁

₂

₃

Preferably, the emulsifying substance consists of the first mixture.
Preferably, the first mixture is used in an amount of 5-10 g per 100 g of the suspension.
Preferably, the emulsifying substance consists of the first mixture and the second mixture.
Preferably, the first mixture is used in an amount of 5-10 g per 100 g of the suspension, and the second mixture is used in an amount of 1 g per 100 g of the suspension.
Preferably, the emulsifying substance consists of the first mixture and the third mixture.
Preferably, the first mixture is used in an amount of 5-10 g per 100 g of the suspension.
Preferably, the emulsifying substance consists of the third mixture.
Preferably, the third mixture is used in an amount of 5 g per 100 g of the suspension.
Preferably, zinc oxide is added in an amount of 5 g to 100 g of the emulsion.
Preferably, compound 1 is used in an amount of 90% by weight relative to the first mixture.
The subject of the invention is also a fabric softener containing the concentrate for rinsing fabrics according to the invention, wherein the amount of said concentrate for rinsing fabrics is 15-50 ml per 1 l of the fabric softener.
Preferably, the amount of the concentrate for rinsing fabrics is 20 ml or 40 ml per 1 l of the fabric softener.
The subject of the invention is also use of the concentrate for rinsing fabrics according to the invention or the fabric softener according to the invention, for rinsing fabrics, said concentrate for rinsing fabrics or said fabric softener being used in any of the stages of the washing cycle or in the last stage of a fabric washing cycle.
Preferably, said fabric contains 10-40% of polyester and said fabric has undergone two to five washing cycles after the use of said concentrate for rinsing fabrics or fabric softener.

Preferable effects of the invention

The concentrate according to the invention and the fabric softener according to the invention result in lasting bacteriostatic, softening and antistatic properties of fabrics. In addition, they also provide lasting fungicidal properties.
The invention provides the generation of a lasting protective layer, also entering between the splices of textile fibres. The generation of the layer occurs during a simple application, which can best be likened to the action of a fabric softening agent during rinsing in typical washing cycles. The invention is also characterised by the simplicity of dosage and the ability to reapply and renew the active ZnO coating. Functionality provided in such a manner allows more lasting protection and longer maintenance of fabrics in a state of resistance to bacteria (compared to unprotected fabrics).
The use of the invention facilitates fighting microorganisms; it improves prevention and protection against dangerous microbes, and it minimises the risk of infections and epidemics, e.g., in hospitals, hotels and hospices. The concentrate for rinsing fabrics and the fabric softener, according to the invention can be used by laundries and mangling facilities, providing services, e.g., for hospitals. Because of the invention, laundries washing, e.g., hospital bedlinens and sheets, will be able to deliver fabrics containing no live microbes or their endospore forms. The invention is also useful in laundries ensuring ultra-high bacterial purity.
The concentrate according to the invention and the fabric softener according to invention can be additionally used in washing machines in households, and even while washing by hand.
An important aspect of the developed invention involves the use of agents which do not damage fabrics and are safe for the environment. Components of the invention have no negative impact on the longevity of washing devices (e.g., washing machines) and their operation.
Zinc oxide (ZnO) is an active substance which acts toxically towards bacteria. A person skilled in the art will recognise that the used ZnO particles are of relatively small sizes. Studies performed as part of the invention have indicated that, in one example, the used grains had a size of 0.063 mm (sieve analysis).
Zinc oxide particles induce considerable morphological changes of a bacterial cell membrane, inhibiting the growth of the cell and effectively leading to its death. The results of research performed for the invention confirm the bactericidal properties of this oxide. During rinsing, ZnO is adsorbed on the surface of the fabric, resulting in its bactericidal and fungicidal properties.
In addition, zinc oxide is a safe substance, used as a component of dermatological, cosmetic products permitted for use by way of a decision of the European Commission. The selected active substance fulfils requirements faced by materials used in the pharmaceutical and cosmetic industry for the production of tablets, creams, pastes and emulsions. It has high purity, it is not toxic and it is allowed for use by humans.
In the invention, ZnO has been mixed with an emulsifying substance, which has a softening effect on fabrics and simultaneously lowers the aggregation of ZnO particles. More precisely, zinc oxide used for coating fabrics is suspended in a proper emulsifying substance, which serves two functions: it has to suspend zinc oxide particles in a homogeneous manner forming a stable emulsion, and also, it has to facilitate homogeneous adsorption (attachment) of ZnO onto fabric with the generation of a coating with the highest possible durability, ensuring antibacterial action of zinc oxide.
The produced concentrate according to the invention is universal in terms of its use, i.e. the possibility of its application on fabrics with a varying composition, and universal in terms of action, i.e. the absence of any additional conditions for the activation of bactericidal properties, such as, e.g., catalysts, light (e.g., UV radiation), temperature or any other external factor/stimulus available for a person skilled in the art. At the same time, nothing prevents said additional conditions from being used in order to enhance the advantageous effect of the invention.
Application of the concentrate (or fabric softener) according to the invention onto a textile material involves the addition of a specified volume of concentrate in one of the stages of the washing cycle, e.g., during the final rinsing of already washed fabrics. It is a particular advantage of the concentrate according to the invention, since it has a simple mechanism of application, involving its addition, for example to the final rinsing cycle, like typical concentrates for softening fabrics, commonly used in laundries. Therefore, the use of the invention requires neither additional activation of the washing cycle nor increasing the energy consumption of the entire washing method. In other words, from the user's point of view the invention requires no introduction of any changes to the washing technology.
Further preferable effects of the invention are presented in embodiments and in the drawings.

Brief description of Figures

In order to depict the invention and its operating principles, the application has drawings attached to it, in which:

Fig. 1 presents sample microscopic images of a unicolour cotton fabric (90%cotton/10% polyester):
- left-hand side: unmodified fabric,
- right-hand side: fabric modified with 0.5% of ZnO/emulsifying substance.
Fig. 2 presents sample microscopic images of a ribbed polyester fabric (60%cotton/40% polyester):
- left-hand side: unmodified fabric,
- right-hand side: fabric modified with 0.5% of ZnO/emulsifying substance.
Fig. 3 presents sample microscopic images of a fabric with carbon fibre (99% polyester/1% carbon fibre):
- left-hand side: unmodified fabric,
- right-hand side: fabric modified with 0.5% of ZnO/emulsifying substance.
Fig. 4 presents sample SEM images of samples of a unicolour cotton fabric (90% cotton/10% polyester):
- left-hand side: unmodified fabric,
- right-hand side: fabric modified with 0.5% of ZnO/emulsifying substance.
Fig. 5 presents sample SEM images of a polyester ribbed fabric (60% cotton/40%polyester):
- left-hand side: unmodified fabric,
- right-hand side: fabric modified with 0.5% of ZnO/emulsifying substance.
Fig. 6 presents sample SEM images of fabric with carbon fibre (99% polyester/1% carbon fibre):
- left-hand side: unmodified fabric,
- right-hand side: fabric modified with 0.5% of ZnO/emulsifying substance.

Embodiments

In the following part of the description, the invention is presented by means of embodiments illustrating various aspects of the invention. The embodiments also show the efficiency of the invention and further preferable effects. The presented embodiments, including the manner of their detailed implementation, do not limit the scope of the invention in any way. All obvious modifications and variants of the invention, as well as the use of equivalent means, fall within the scope of the invention.

MATERIALS

Tallow and coconut oil were used in the embodiments as a source of fatty acids. Tallow may be of various origins; therefore, the composition of tallow is subject to changes. Coconut oil also contains a mixture of fatty acids. Due to the nature of the concentrate (emulsion / suspension) and permitted changes in the composition of constituents which form it, the composition of the concentrate according to the invention cannot be determined directly. However, there is a possibility to define the concentrate by the manner of its preparation.
The invention can use any isopropyl alcohol, hexadecan-1-ol, butylene glycol with purity approved for use in concentrates for rinsing fabrics. In more specialised applications, like hospital or ultra-clean laundries, it may be required to use these substances with higher purity.
Polyvinyl alcohol (PVA) was also tested as an emulsifying substance. Hence, the embodiments presented below also include a disclosure in the form of a combination of zinc oxide and polyvinyl alcohol.
Water used in the invention may have any purity allowed for use in concentrates for rinsing fabrics and fabric softeners. In more specialised applications, like hospital or ultra-clean laundries, it may be required to use water with selected parameters.
Commercial preparations listed in the embodiments may be used directly, i.e. with no further treatment and purification.

APPARATUS

In order to produce concentrates according to the invention, heating was performed using an ordinary heater, but it is possible to use any other heating means, which do not cause disintegration of the components of the resulting concentrate. Stirring was performed with the use of standard laboratory apparatus.
Diffuse reflectance spectra were recorded by means of a UV-Vis spectrophotometer provided with an integrating sphere.
Purity tests were performed using the Luminometer apparatus, whose operation is based on bioluminescent measurements.
The imaging of samples was performed by means of an optical microscope. More detailed imaging of samples was performed by means of a scanning electron microscope.

ZINC OXIDE SPECTRUM

A benchmark diffuse reflectance spectrum of clean zinc oxide was measured in a pellet of BaSO₄, using pure barium sulphate(VI) as the reference. A drop in reflectance at 380 nm, characteristic for ZnO, was determined on the spectrum.
Upon conversion into an absorption spectrum by means of the Kubelka-Munk function (K-M), this spectrum is characterised by a clear increase in absorbance at a wavelength of approx. 380 nm. The characteristic drop in reflectance or increase in absorbance at a wavelength of 380 nm (when changing the wavelength from longer to shorter) was used as confirmation of the presence of zinc oxide on the tested material, e.g., on a modified fabric.
For comparison, diffuse reflectance spectra were depicted for representative types of fabrics: a polyester ribbed fabric containing 40% of polyester and 60% of cotton, and a fabric with an addition of carbon fibre with a composition of 99% polyester and 1% carbon fibre modified with ZnO/water suspensions with various concentrations of zinc oxide. For unmodified fabrics, the increase in reflectance/Kubelka-Munk function at a wavelength of 380 nm, characteristic for the presence of ZnO, was not observed. A relatively weak signal from ZnO was observed on slippery and electrically charged fabrics with carbon fibre.

LABORATORY WASHING PROCEDURE

A number of tests were performed in order to determine the behaviour of representative fabrics under the conditions of washing, rinsing, spinning, drying and mangling. In this manner, a point of reference was also established for testing the invention.
Fragments of fabrics with dimensions of 2 cm x 2 cm were submerged in a suspension of zinc oxide with a concentration of 0.50% and stirred in a magnetic stirrer with a rotational speed of 1500 min^-1 for approximately 10 minutes, spun, dried and ironed. For fabrics modified with water suspensions of ZnO, reflectance spectra were recorded with a spectrophotometer. Fabrics with applied zinc oxide were washed and rinsed according to the following procedure:
I. The washing stage: the fabrics were submerged in a solution of detergents: 0.5 ml of Septonite and 0.5 ml of Break in 250 ml of warm tap water and stirred for approximately 15 minutes on a magnetic stirrer with a rotational speed of 1500 min^-1. Septonite and Break were used as detergents and bleaching agents utilised in industrial laundries.
II. The rinsing stage: the fabrics were submerged in a solution created as a result of stirring 1.5 ml of 1 M CH₃COOH with 250 ml H₂O of cold tap water and stirred for approximately 10 minutes on a magnetic stirrer with a rotational speed of 1500 min^-1.
III. The spinning stage: the fabrics were submerged in water and placed in a centrifuge for about 5 minutes with a rotational speed of 2000 min^-1.
IV. The drying stage: after spinning, fabrics were put in an oven at a temperature of 170°C for approximately 15 minutes.
V. The mangling stage: dried fabrics were ironed using an iron at a temperature of approximately 220°C.
In another version, the laboratory washing procedure was performed using the Jeleń washing powder and fabric softener available in retail sale.
In the following part of the description, reference to laboratory washing means implementation of the procedure described above.
After the performance of each procedure of washing with rinsing, diffuse reflectance spectra were recorded for 3 types of fabrics, i.e. cotton, polyester and fabric with carbon fibre, with a qualitative assessment of the durability of ZnO coating applied onto the fabric.
Each subsequent washing caused a drop in the amount of ZnO on the fabric. For unmodified fabrics, no increase in reflectance/the Kubelka-Munk function was observed at a wavelength of 380 nm.

PRODUCTION OF CONCENTRATES FOR RINSING FABRICS

Possible combinations of embodiments related to the production of concentrates according to the invention and versions of these embodiments also fall within the scope of the invention. In particular, there are considerations of possible combinations of versions of embodiment 1 or possible combinations of embodiments 2-5 and their versions.

Embodiment 1

An emulsifying substance was used in the form of a first mixture containing compound 1 with the following formula:
where R₁O and R₂O are ester groups of one or more fatty acids derived from tallow, compound 1 being used in an amount of 85-95% by weight relative to the first mixture, and the rest of the first mixture consisting of isopropyl alcohol.
Therefore, compound 1 also represents a mixture produced, e.g., via diesterification of triethanolamine with one or more fatty acids derived from tallow. This means that the R₁O and R₂O groups may be the same or different. In one version, compound 1 represents a mixture of diesters resulting from diesterification with a mixture of fatty acids derived from tallow. In yet another version, compound 1 was produced using a mixture of fatty acids from tallow with the composition of fatty acids present in tallow.
In one version of this embodiment, the mixture which was used originated from animal tallow, including beef tallow. In another version, 90% by weight of compound 1 was used relative to the first mixture.
A preparation with the trade name Tequat^® LC 90i from PCC Group, Poland, is a preferable example of the first mixture. This product is sometimes described as a mixture of quaternary methylsulphates of diesters of fatty acids and triethanolamine in isopropyl alcohol.
The first mixture was suspended in water.
In the suspension, the first mixture was used in an amount of 4-12 g and water was used as a complement. In another version, the first mixture was used in an amount of 5-10 g and water was used as a complement. However, the most preferable results were achieved using 5 g or 10 g of the first mixture. In particular, the version containing 5 g of the first mixture and 95 g of water was the most preferable.
The suspension was heated up to a temperature of 80°C while being intensely stirred. Heating and stirring resulted in the generation of an emulsion.
Zinc oxide was added to the emulsion prepared in this manner. Zinc oxide was added in an amount of 4-6 g to 100 g of the resulting emulsion, but the best results were achieved when adding zinc oxide in an amount of 5 g to 100 g of the resulting emulsion. In one version, zinc oxide was introduced into the emulsion which was intensely stirred and/or heated to a temperature of 80°C.

Embodiment 2

This embodiment is a version of embodiment 1, in which the first mixture was used in an amount of 10 g, with water in an amount of 90 g.
In one version, the Tequat^® LC 90i preparation from the PCC Group, Poland, was used.

Embodiment 3

This embodiment is a version of embodiment 1, in which the used emulsifying substance consisted of the first mixture defined in embodiment 1 and a second mixture containing docosyltrimethylammonium methyl sulphate in an amount of 45-55% by weight relative to the second mixture, hexadecan-1-ol in an amount of 35-45% by weight relative to the second mixture, as well as butylene glycol as a complement of the second mixture, said butylene glycol being used in an amount of no more than 10% by weight relative to the second mixture.
In one version, docosyltrimethylammonium methyl sulphate was used in an amount of 50% by weight relative to the second mixture.
In another version, a preparation with the trade name BTMS-50 was used as the second mixture.
The amount of used emulsifying substance was 4-12 g per 100 g of the suspension. Very good results were achieved in versions where the emulsifying substance was used in an amount of 5 g or 10 g per 100 g of the suspension.
Exceptionally good results were achieved when using 5-10 g of the first mixture and 1 g of the second mixture, and the best with 10 g of the first mixture and 1 g of the second mixture.

Embodiment 4

This embodiment is a version of embodiment 1, in which instead of the first mixture, the used emulsifying substance consisted of a third mixture containing compound 2 with the following formula:

where R₃ is an n-alkyl chain or an n-alkenyl chain with 8 to 16 carbon atoms, and n = 15 or 16.
Therefore, compound 2 also represents a mixture of amines. This means that, in one version, compound 2 is an amine containing an n-alkyl chain with a specified length (carbon number, e.g., 8, 9, 10, 11, 12, 13, 14, 15 or 16), and in another version it is an n-alkenyl chain with a specified length (carbon number, e.g., 8, 9, 10, 11, 12, 13, 14, 15 or 16). In another version, compound 2 was generated using a mixture of fatty acids produced from coconut oil. In yet another version, compound 2 was generated using a mixture with a composition of fatty acids corresponding to the composition of coconut oil.
In another version, a preparation with the trade name ROKAmin K15K from the PCC Group, Poland, was used as the third mixture. This preparation is sometimes described as an ethoxylated and quaternised fatty amine.
In the most preferable version, the third mixture was used in an amount of 5 g per 100 g of the suspension.

Embodiment 5

This embodiment is a version of embodiment 4, where a mixture of the first and third mixtures is used as an emulsifying substance.
The first and third mixture can be used in various proportions. However, it is important for the amount of the emulsifying substance in 100 g of the suspension to fall within a scope of 4-12 g. In a preferable version, the emulsifying substance was used in an amount of 5-10 g per 100 g of the suspension.
In the most preferable version, the first and third mixtures were used in a weight ratio of 1 : 1. In one version, the first mixture was used in an amount of 5 g per 100 g of the suspension and the third mixture was used in an amount of 5 g per 100 g of the suspension.

PRODUCTION OF FABRIC SOFTENERS

Embodiment 6

This embodiment involves fabric softeners containing concentrates described in embodiments 1-5 in a dilution of 50 times or higher and reaching 25 times. The concentration of the fabric softener according to the invention was increased twice in order to achieve a stronger bacteriostatic effect.
In one version, 2 I of water consumed in the rinsing cycle were used along with 40 ml of one or more concentrates according to the invention. In particular, concentrates according to embodiments 1-5 were used.

TESTS OF FABRICS MODIFIED WITH ZINC OXIDE WITH AN EMULSIFYING SUBSTANCE

Embodiment 7

Fragments of fabrics with dimensions of 2 cm x 2 cm were submerged in a suspension of zinc oxide with a concentration of 0.5% and 1.0% of an emulsifying substance (e.g., polyvinyl alcohol, PVA) and stirred on a magnetic stirrer with a rotational speed of 1500 min^-1 for approximately 10 minutes, spun, dried and ironed using an iron at a temperature of approximately 220°C. For fabrics modified with the use of ZnO/an emulsifying substance, diffuse reflectance spectra were recorded using a spectrophotometer. Fabrics with applied zinc oxide were washed and rinsed according to the laboratory washing procedure described above.
After each stage of washing with rinsing, diffuse reflectance spectra were recorded for 3 types of fabrics, i.e. cotton, polyester and a fabric with carbon fibre, assessing the efficiency of the ZnO coating applied onto the fabric.
Diffuse reflectance spectra were recorded for fabrics which had been modified and subjected to washing. The highest decrease in reflectance/increase in the Kubelka-Munk function at a wavelength of 380 nm was observed for fabrics directly after applying a suspension of ZnO with an emulsifying substance. During laboratory washing and rinsing, a drop in the zinc oxide content was observed in all tested fabrics; however, even after 5 cycles of laboratory washing and rinsing, the presence of zinc oxide on the fabric was still recorded for each one of the tested fabrics. In laboratory examinations, it was confirmed by spectroscopic tests that the drying and mangling stages do not affect the amount of zinc oxide deposited on fabrics.

MICROSCOPIC EXAMINATIONS

Embodiment 8

EXAMINATIONS USING AN OPTICAL MICROSCOPE

Fragments of fabrics were imaged by means of an optical microscope, and the presence of zinc oxide was confirmed on materials modified with ZnO. No presence of ZnO was observed on unmodified fabrics, sample images being presented in figs. 1-3 (left-hand side).
It should be pointed out that the presence of ZnO in the disclosed concentrations does not affect the appearance of cloth; in particular, it does not change its colour and it does not cause the generation of stains.

EXAMINATIONS USING AN ELECTRON MICROSCOPE

The analysis involved the degree/uniformity of coverage of fabric samples modified with zinc oxide and unmodified fabrics. It has been observed that ZnO is located on fabrics in regularly distributed areas (visible as bright spots on the images). The resulting images of materials are presented in sequence in figs. 4-6. The images have confirmed the presence of ZnO on the surface of fabrics modified with ZnO (images on the right-hand side); no ZnO was observed on the surfaces of unmodified fabrics (images on the left-hand side).
In a microscopic image, higher homogeneity of the distribution of zinc oxide on the surface of fabrics is exhibited by samples with an addition of an emulsifying substance.
Laboratory tests have confirmed that the invention enables the application of ZnO onto the surfaces of fabrics in a simple manner. This application involves spreading the concentrate according to the invention or the fabric softener according to the invention in one of the washing stages (e.g., in the rinsing stage). In particular, spreading is performed in the final stage of washing and/or in the final stage of rinsing, since it ensures less washing out of the active substance from the fabrics.

TESTS OF THE MICROBIOLOGICAL PURITY OF THE SURFACES OF FABRICS USING THE LUMINOMETER

Embodiment 9

Samples of three types of fabrics were prepared for an analysis of microbiological purity: cotton, ribbed polyester and polyester material with carbon fibre. A sterile Lucipack Pen tip was used to collect swabs of fabric with surface areas of 2 cm x 2 cm, moisturised with demineralised water.
Samples of each of the 3 types of fabrics were collected, having previously been:

modified with a suspension of zinc oxide in water, dried and ironed;
modified with a suspension of zinc oxide with an emulsifying substance, dried and ironed;
modified with a suspension of zinc oxide in water, dried and ironed, then washed and rinsed five times in a washing machine;
modified with a suspension of zinc oxide with an emulsifying substance, dried and ironed, washed and rinsed five times (laboratory washing);
not modified with zinc oxide, subjected to washing, drying and ironing;
unmodified, additionally contaminated (rubbed wet against the surfaces of door handles).

For sterile surfaces, results presented in RLU units should not exceed a value of 50 RLU. The results of tests are presented in table 1.
For the surfaces of fabrics modified with zinc oxide, much lower values of microbiological purity were achieved compared to unmodified fabrics. Even fabrics after five times of washing and rinsing exhibit lower values of RLU compared to unmodified fabrics, subjected to similar laundering procedures. The presented results indicate a more lasting effect of the action of modification using zinc oxide with an emulsifying substance according to the invention.

The invention is already effective after the first use. Unexpectedly, much higher efficiency of the invention was observed after the performance of at least two, and most preferably five cycles of washing, rinsing, drying and ironing for fabrics with a polyester content within a range of 10-40%. In particular, for fabrics with a polyester content of 10% or 40%.

Table 1. A list of the results of microbiological purity measurements for the surfaces of fabrics using a Luminometer analyser (averaged results from three repetitions).

Fabric preparation type	RLU value for a unicolour cotton fabric (90% cotton/10% polyester)	RLU value for a ribbed polyester fabric (60% cotton/40% polyester)	RLU value for a fabric with carbon fibre (99% polyester/1% carbon fibre)
Modification with a suspension of zinc oxide in water, drying and ironing	12	16	79
Modification with a suspension of zinc oxide with an emulsifying substance, drying and ironing	26	18	60
Modification with a suspension of zinc oxide in water, drying and ironing, followed by washing and rinsing five times, drying and ironing	64	45	24
Modification with a suspension of zinc oxide with an emulsifying substance, drying and ironing, followed by washing and rinsing five times, drying and ironing	37	29	72
Washing, drying and ironing, with no additional modifications	251	93	148
Additional contamination (wet rubbing against the surfaces of door handles)	1224	1016	609

ZnO attached to the surface of a fabric results in its bactericidal activity. Under laboratory conditions, it was observed that bactericidal activity is maintained for 5 cycles of washing and rinsing. Tests involving reapplication of zinc oxide have confirmed that a new application of the protective coating and restoration of the antibacterial properties of fabrics can be done with no problems. A safe and easy composition was produced, one which will require no significant changes in industrial washing procedures. Moreover, the invention enables simple application under the conditions of home washing and it will cause no increase in the operating costs, including increased consumption of water and energy.

Claims

A concentrate for rinsing fabrics, wherein said concentrate for rinsing fabrics can be produced via the following stages:
• suspending an emulsifying substance in water in order to produce a suspension,

• heating the resulting suspension at a temperature reaching or equal to 80°C under atmospheric pressure along with intense stirring of the suspension in order to produce an emulsion, followed by

• adding zinc oxide to the resulting emulsion,
wherein the emulsifying substance is used in an amount of 4 to 12 g per 100 g of the suspension and the rest of the suspension consists of water, and wherein zinc oxide is added in an amount of 4 to 6 g to 100 g of the emulsion, and
wherein the emulsifying substance contains
a first mixture containing compound 1 with the following formula:
where R₁O and R₂O are ester groups of one or more fatty acids derived from tallow, compound 1 being used in an amount of 85-95% by weight relative to the first mixture, and the rest of the first mixture consisting of isopropyl alcohol, and/or
a second mixture containing docosyltrimethylammonium methyl sulphate in an amount of 45-55% by weight relative to the second mixture, hexadecan-1-ol in an amount of 35-45% by weight relative to the second mixture, as well as butylene glycol as a complement of the second mixture, said butylene glycol being used in an amount of no more than 10% by weight relative to the second mixture, and/or
a third mixture containing compound 2 with the following formula:

where R₃ is an n-alkyl chain or an n-alkenyl chain with 8 to 16 carbon atoms, and n = 15 or 16.
The concentrate for rinsing fabrics according to claim 1, characterised in that the emulsifying substance consists of the first mixture.
The concentrate for rinsing fabrics according to any of the preceding claims, characterised in that the first mixture is used in an amount of 5-10 g per 100 g of the suspension.
The concentrate for rinsing fabrics according to claim 1, characterised in that the emulsifying substance consists of the first mixture and the second mixture.
The concentrate for rinsing fabrics according to any of the claims 1 or 4, characterised in that the first mixture is used in an amount of 5-10 g per 100 g of the suspension, and the second mixture is used in an amount of 1 g per 100 g of the suspension.
The concentrate for rinsing fabrics according to claim 1, characterised in that the emulsifying substance consists of the first mixture and the third mixture.
The concentrate for rinsing fabrics according to any of the preceding claims, characterised in that the first mixture is used in an amount of 5-10 g per 100 g of the suspension.
The concentrate for rinsing fabrics according to claim 1, characterised in that the emulsifying substance consists of the third mixture.
The concentrate for rinsing fabrics according to any of the claims 1 or 6 or 8, characterised in that the third mixture is used in an amount of 5 g per 100 g of the suspension.
The concentrate for rinsing fabrics according to any of the preceding claims, characterised in that zinc oxide is added in an amount of 5 g to 100 g of the emulsion.
The concentrate for rinsing fabrics according to any of the claims 1-7, characterised in that compound 1 is used in an amount of 90% by weight relative to the first mixture.
A fabric softener containing the concentrate for rinsing fabrics according to any of the preceding claims, wherein the amount of said concentrate for rinsing fabrics is 15-50 ml per 1 I of the fabric softener.
The fabric softener according to claim 12, characterised in that the amount of the concentrate for rinsing fabrics is 20 ml or 40 ml per 1 l of the fabric softener.
Use of the concentrate for rinsing fabrics according to any of the claims 1 to 11 or the fabric softener according to any of the claims 12-13 for rinsing fabrics, said concentrate for rinsing fabrics or said fabric softener being used in any of the stages of the washing cycle or in the last stage of a fabric washing cycle.
The use of the concentrate for rinsing fabrics or the fabric softener according to claim 14, characterised in that said fabric contains 10-40% of polyester and said fabric has undergone two to five washing cycles after the use of said concentrate for rinsing fabrics or said fabric softener.