DE102015001669A1 - Cleaning, washing and / or polishing substrate consisting of textile and / or non-woven and / or sponge-like structures for cleaning surfaces of any kind with antimicrobial properties - Google Patents

Abstract

Cleaning, washing and / or polishing substrate (10) consisting of textile and / or nonwoven and / or sponge-like structures for cleaning surfaces of any kind with antimicrobial properties using copper (I) oxide microparticles (9) having a particle size in the range of 1-10 microns, wherein on the surface of the substrate (10) an elastomeric coating (4) is attached, which consists of an elastomeric carrier substance (8) and the incorporated therein copper (I) oxide particles (9) ,

Description

The invention relates to a cleaning, washing and / or polishing substrate consisting of textile and / or non-woven and / or sponge-like structures for cleaning surfaces of any kind with antimicrobial properties according to the subject-matter of patent claim 1.

More particularly, the invention relates to the use of copper (I) oxide microparticles having a particle size in the range of 1-10 microns, wherein adhered to the surface of the substrate is a film-forming elastomeric coating composed of an elastomeric support and copper (II) incorporated therein. I) oxide particles.

The antibacterial and antimicrobial properties of copper (I) oxide are known. The ratio formula is Cu ₂ O.

The thermal decomposition of the copper (I) oxide crystals takes place at about 1,800 ° C. The substance is insoluble in water but soluble in dilute acids.

Copper (I) oxide is a chemical compound that contains copper and oxygen. In this oxide with the empirical formula Cu ₂ O, copper is monovalent. Copper (I) oxide is a yellow to red-brown solid and turns black on heating, but returns to its original color after cooling.

The DE 10 2007 003 648 A1 and the DE 10 2007 003 649 A1 propose a molding material comprising polyester containing copper (II) salts, wherein the copper-containing particles are present in a size of 0.1 nm to 200 μm, preferably 1 nm to 100 μm, in particular from 0.1 μm to 50 μm.

From the copper-containing molding material of polyester, a yarn can be produced by a melting process. Both staple fibers and filaments can be made. Disadvantage of the known production method and the yarn produced therefrom is that the polyester mass surrounds the copper particles, that the copper particles enclosed in the polyester mass no longer reach the surface and their antimicrobial activity only to a small extent, or at very high, ecologically unacceptable amounts can unfold. The partially recommended nanoscale particles have a high dissolution rate due to their high surface energy, which, although a short-term high effect, but correspondingly rapidly by the substantial removal of the particles leads to a reduction or the complete loss of antimicrobial action.

Due to the complete inclusion of nanoscale scaled particles, the antimicrobial effect of yarns made according to the above two references is low.

Incidentally, the use of nanoscale copper particles encounters physiological concerns because of the danger of introducing these particles into human or animal tissue.

Although the description uses the DE 10 2007 003 649 A1 expressly the term "microparticles and microparticle products", however, meaning nanoscale particles which are to be applicable, inter alia, to disposable or reusable cleaning and wiping cloths and towels as well as household sponges and cosmetic sponges. The invention is based on the same field of application as mentioned above, but the antimicrobial action of the above-described cleaning, washing and polishing substrates, which preferably consist of textile and / or flow-like and / or sponge-like structures, should be substantially improved and those above Be physiologically harmless.

The solution of the problem is achieved by the technical teaching of claim. 1

A preferred process for the preparation of said cleaning, washing and / or polishing substrates is the subject of independent claim 7.

A feature of the invention is that it dispenses with nanoscale copper (I) oxide particles and instead prefers a particle size in the range from 1 to 10 .mu.m, which are physiologically harmless and in which there is no risk of introduction into the human or animal tissue consists.

Another feature of the invention is that the invention according to the technical teaching of independent claims 1 and 7 is not dependent on the production of a yarn, which in its manufacture already equipped antimicrobial, but the invention provides in a much later processing aid the equipment of a cleaning, washing and polishing substrate with an antimicrobial coating.

The antimicrobial finish of a cleaning, washing and / or polishing substrate according to the invention thus takes place in a substantially later process step than in the case of the abovementioned prior art, in which the yarn itself was already the subject of the antimicrobial finish.

The invention thus has the advantage that any cleaning, washing and / or polishing substrates already produced can be provided with an antimicrobial coating, which was hitherto unknown.

Copper-containing particles are of great interest for antibacterial activity on textiles or sponges or nonwovens for cleaning purposes, as well as for medical articles, sanitary applications or the like, in which odor formation can be controlled as a consequence of bacterial activity. The Cu (I) oxide microparticles of the invention having a uniform diameter between 1.5 and 2 microns; can be prepared according to the invention by controlled reduction of alkaline Cu (II) -tartaric acid complexes.

Such particles are attached to the substrate surfaces, in particular to textile surfaces by means of a pigment binder system.

The pigment binder system has hitherto been used technically only for pigment dyeing, but not for the surface coating of substrates consisting of textile and / or nonwoven and / or sponge-like structures.

In a preferred embodiment, the coating is carried out by a pad-dry process with which a textile fabric having a Cu content of 250 to 270 mg Cu / kg of substance could be produced.

The test protocol for immobilized antimicrobial agents under dynamic contact conditions ASTM E2149-01 Issued samples showed a 100% survival reduction against Staphylococcus aureus and 84% against Klebsiella pneumoniae.

In simulated washing procedures it could be shown that a reduction of the Cu content of the coating to 60-50% compared to the initial value still achieved a reduction of the viability of 99% compared to Staphylococcus aureus and 78% to Klebsiella pneumoniae.

Accordingly, it has been found that the manufacturing process is of high value to impart antimicrobial properties to cleaning, washing and / or polishing substrates because simple processes and low cost chemicals have been used to provide an antimicrobial cleaning and cleaning product which is good Has washing permanence.

The present invention, as one possible embodiment, describes the preparation of an antimicrobial fabric from PES microfiber fabric using Cu (I) microparticles. However, the invention is not limited to textile fabrics.

Only the simpler description describes the application of the invention to textile fabrics, although the field of application of the invention relates to all cleaning, washing and / or polishing substrates, regardless of whether such substrates are woven, knitted or knitted structures (eg. Cleaning cloths, cloths and the like.) Are present. Likewise, the invention relates to the application in nonwovens or natural or synthetic sponges for cleaning purposes. Similarly, metallic sponges, especially stainless steel sponges should be provided with the antimicrobial finish.

Accordingly, when the application to a textile is described in the following description, it is not intended to be limiting.

1. Preparation of the Cu (I) Microparticles:

The Cu (I) microparticles were obtained by reduction of alkali Cu (II) -tartaric acid complexes. The particles produced therefrom are removed in the wet state from the bath used for the production and further processed in the wet state.

This has the distinct advantage that the particle body enclosing a Hydratmantel is retained on the particles and the particle is introduced with the adhering aqueous hydrate coat in a polymer binder system which produces the coating composition on the surface of the substrate.

Frequently, Cu-oxide particles are generated by thermal processes, which leads to chemically very inactive particle surfaces. As a result, in the case of particles produced in this way, low removal rates during leaching and thus low antimicrobial activity result.

Unexpectedly, by using undried Cu (I) oxide microparticles, it was possible to obtain a reactive surface which, after being embedded in the coating composition, leads to useful leaching of Cu ions, without complete removal of all copper already taking place on multiple washes.

In addition, the effect of the embedding agent reduces the surface area of the microparticles in the film-forming elastomeric coating composition by the enveloping shell and advantageously reduces undesirable rapid leakage, so that the antimicrobial effect is maintained over several washes.

Because of the at least 10 times the diameter of the particles used compared to nanoscale particles, a controlled release effect (leaching effect) from the film-forming coating is ensured when a substrate equipped with the particle-bearing coating is used for cleaning purposes.

Since these particles have no affinity for textile fibers, nonwovens and yarns, in particular polyester fibers, a polymer binder system was used according to the invention, the application of which was previously known only for the dyeing of textile substrates with pigments.

With the polymer binder system according to the invention, the microparticles are attached to the fiber surface. The technical concept is not dependent on a particular fiber property. It can thus be used for most of the currently used textile fibers (but also for all other previously mentioned substrates).

The treated tissue was examined by FTIR spectroscopy, the determination of the Cu content and the antimicrobial properties against Staphylococcus aureus and Klebsiella pneumoniae were determined. Likewise, the washing permanence was tested.

The presented technique of immersion coating or spray coating can be adopted on existing textile machines without significant changes. Therefore, there is no need for a change in the production process of textile and / or sponge-like plaster substrates.

2. Test material and chemicals

Two different polyester based knits were used for the experiments. Details are given in Table 1 according to ANNEX.

The following substances were used on chemicals:
CuSO4.5H2O (Fluka, Buchs, Switzerland), potassium sodium tartrate tetrahydrate KNaC4H4O6.4H2O (Zeller, Dornbirn, Austria), NaOH, HNO3 and glucose monohydrate (Merck, Darmstadt, Germany) as reagent grade reagents.

As polymer binder system z. B. an acrylonitrile-butadiene-styrene copolymer emulsion (ABS binder) used (substance with the trade name "Tubifast BN35" (acrylonitrile-butadiene-styrene copolymer, Austria CHT Fa. R. Beitlich, Meiningen, Austria)) and as Dispersant the substance with the brand name "Setamol WS" (lignosulfonate, BASF, Ludwigshafen, Germany) used.

3. Preparation of Cu2O microparticles

For the preparation of the microparticles Cu2O, 100 ml solution of glucose monohydrate (10 g / l, 0.050 M) was added to 100 ml of solution containing CuSO4.5H2O (3 g / l, 0.012 M), potassium sodium tartrate tetrahydrate (20 g / l, 0.071 M) ) added together with NaOH (5 g / l, 0.125 M) combined.

The mixture was heated in a water bath at 80 ° C for 1 h to conduct the reduction reaction.

The settled on the bottom, colorless microparticles were removed and the supernatant decanted. The particles were rinsed three times with distilled water.

4. Impregnation of textile fabrics

The resulting microparticles were used to impregnate the fabric, but without intermediate drying by adding in 200 ml of an aqueous solution of the ABS copolymer-based binder (Tubifast BN35, 50 g / L) and a dispersing agent to the dispersion in the solution support (Setamol WS, 5 g / l).

The impregnation of samples (31 × 20.5 cm) was carried out on a laboratory coating unit (RT, speed 0.5 m / min, nip pressure 2 bar). The samples were then treated in hot air at 150 ° C for 5 minutes to fix the Cu2O particles to the fabric with the binder system. Two samples of each quality were made.

For the simulated washing samples, the prepared samples were placed in 250 ml bottles in a 250 ml cleaning solution. The detergent with the brand name "Claro" from Claro Produkte, Mondsee, Austria was diluted to 1 g / l tap water.

The samples were then treated in a water bath at 60 ° C for 30 minutes. The procedure was repeated 5 times or 10 times. The samples were then dried at ambient conditions for 24 hours.

5. Results and discussion

Cu2O microparticles

The production of the Cu2O microparticles was carried out in an adapted reaction scheme of Fehling's test for aldehydes. Glucose was used as the reducing aldehyde and an alkaline solution of Cu (II) -tartaric acid complex was added as a source of Cu (II) ions. The rate of reduction can be controlled by adjusting the concentration of NaOH in the sample and by temperature.

Smaller particles are produced when a rapid formation of Cu2O near the boiling point occurs. By reducing the NaOH concentration, slow controlled growth of microparticles up to a mean diameter of about 1.5 to 2 microns could be achieved.

The settled Cu2O microparticles were rinsed with water to remove the chemicals from the reduction step. The particles were then used directly to prepare the aqueous dispersion to initiate the impregnation.

Preparation of the textiles

The textile fabrics were impregnated with the dispersion of Cu 2 O particles by means of a laboratory padder. A padder is also referred to as a broad dyeing, padding or padding machine. In her a fleet is pressed by roller pressure into a tissue. It is used for dyeing, impregnation and other finishing processes.

Due to their size, the Cu2O particles can not have strong binding forces to attach to the fiber surface. For this reason, a commercial binder system for pigment dyeing has been used to attach the microparticles to the fiber surface. The uptake of impregnation liquid was found to be 110% w / w for sample A and 64% w / w for sample B. This can be explained by the more closed structure of the polyurethane-coated Sample B.

The Cu content of the samples and reference samples was analyzed by AAS after nitric acid extraction of Cu and appropriate dilution (Table 2).

For comparison, the Cu content of the samples with pigment binder alone was analyzed and a Cu content of about 10 mg Cu per kg of substance was found.

APPENDIX: Table 2 Cu content of the examined tissues and the reference samples.

The durability of the Cu 2 O deposited on the samples and the decrease in Cu content as a function of the 5 × and 10 × repeated simulated washing were investigated and shown in Table 2.

There was a significant decrease in Cu content from initially 248 mg / kg (sample A) and 272 mg / kg (sample B) with increasing number of washes. More than 50% of the Cu content originally bound to the treated samples was detected after 10 washes for Sample B, with 139 mg / kg for Sample A and 170 mg / kg.

This is a much smaller decrease in Cu content compared to results of a similar study where 80% of the Cu was found to be removed during 5 repetitive washes.

The change in tissue surface was also examined by FTIR-ATR spectroscopy.

All three infrared spectra showed the characteristic vibrations for polyester (C = 0) at 1720 cm-1, (CH) at 2920 cm-1 and 2880 cm-1, (CO) at 1250 cm-1, and a smaller amount Polyamides ((NH) at 3300 cm-1). There was no significant difference between the three spectra of the three samples, which difference could indicate the presence of a binder system. This can be explained by the amount of binder on the fabric, which can be estimated to be less than 1% w / w, which is below the detection limit of the test method.

Antimicrobial properties

To determine the antibacterial activity of microparticulate-impregnated fabrics containing Cu2O and comparative samples without Cu2O particles, all samples were tested against Staphylococcus aureus (ATCC 6538, Gram-positive bacteria) and Klebsiella pneumoniae (ATCC 4352, Gram-negative bacteria).

It was after the process ASTM E2149-01 since this standard method is used for the antimicrobial activity of immobilized antimicrobial substances.

Both the fabric itself and the pigment-binder chemistry were shown to significantly reduce the viability of the bacteria.

The subject of the present invention results not only from the subject matter of the individual claims, but also from the combination of the individual claims with each other.

All information and features disclosed in the documents, including the abstract, in particular the spatial design shown in the drawings, are claimed to be essential to the invention insofar as they are novel individually or in combination with respect to the prior art.

In the following the invention will be explained in more detail with reference to drawings showing only one embodiment. Here are from the drawings and their description further features essential to the invention and advantages of the invention.

Show it:

1 : Perspective view of a textile fabric with schematically indicated coating

2 : the section according to the line II-II in 1

3 : schematizes a section through a yarn thread

4 : the enlargement of a fiber from the yarn thread after 3

5 : the magnified representation of the edge area of the fiber after 4

6 : The enlarged schematic representation of the edge region of the coated fiber after 5

7 : Schematically illustrates a first embodiment for coating textile fabric

8th : one opposite 7 modified embodiment

9 : a cleaning cloth, shown schematically, with the coating according to the invention

• Tabelle 1: Cu-Gehalt an unbeschichteten Materialien
• Tabelle 2: Cu-Gehalt an PUR-beschichteten Materialien
• Tabelle 3: antimikrobielle Aktivität verschiedener Testgewebe

10 : Schematically represented a cleaning sponge with the coating according to the invention

• Table 1: Cu content of uncoated materials
• Table 2: Cu content of PUR-coated materials
• Table 3: antimicrobial activity of various test tissues

In 1 is a perspective view of a textile fabric 1 represented, which consists of the intersecting warp and weft threads 2 . 3 is formed.

Each warp and weft 2 . 3 consists of a number of yarns, each forming a bundle 5 ,

It is only schematic and only partially shown that all surfaces of the textile fabric shown 1 with an antimicrobial coating 4 are provided. For the sake of drawing, the coatings are 4 only partially shown, although this over the entire surface and deep into the material of the textile fabric 1 extend into it.

The 2 schematically shows that the weft and warp threads 2 . 3 on all sides of the coating 4 are enclosed.

The 3 shows a yarn as an example 5 which consists of a series of fibers 6 consists.

It is shown that the fibers 6 again according to 4 one fiber body each 7 and the fiber body 7 the fiber 6 is now with the coating according to the invention 4 coated, consisting of an elastomeric carrier substance 8th consists.

The 5 shows that in the elastomeric carrier substance 8th Copper (I) oxide particles 9 (Microparticles) are embedded. Thus, the shows 6 in general terms, that any substrate 10 , in particular the cleaning, washing and polishing substrates specified here with an elastomeric carrier substance 8th can be coated in which microparticles 9 are embedded.

However, it is important that the microparticles 9 in the wet state in the elastomeric carrier substance 8th be embedded, making them from a particle core 11 and a hydrate shell surrounding the particle core 12 consist.

As a result, their binding effect in the vehicle 8th diminished and a proliferation in the direction of the arrow 13 from the surface of the vehicle 8th is relieved.

The composition and surface design of the vehicle 8th is chosen so that it releases the microparticles 9 in the direction of the arrow 13 allowed.

A web coating 14 with the elastomeric carrier substance 8th into which the microparticles 9 are embedded in is 7 shown schematically.

For this purpose, the delivery roller 15 a fabric 14 in the direction of the arrow 16 unrolled and is over the guide rollers 18 . 19 in a dip 17 introduced, which their vehicle 8th is filled in which the microparticles 9 are suspended. It is therefore a dip in the bath 17 arranged pigment binder system 30 with which the coating 4 on the fabric 14 is applied.

After removal from the dip 17 becomes the fabric 14 with a suitable drying unit 12 dried and is thus an impregnated fabric 14 ' containing the antimicrobial coating according to the invention 4 wearing. The thus impregnated fabric is on the winding roller 20 in the direction of the arrow 21 wound.

The in the dipping bath 17 existing coating suspension 19 has the composition as stated in the above general description.

Alternatively to a dip bath according to 7 can also treat a fabric 14 in the manner of a fabric section 23 done in a tenter 24 is clamped. The unit of clamping frame and clamped fabric section 23 is in the arrow directions 25 . 25 ' in a dip 17 sunken in which in turn the pigment binder system 30 is arranged.

From the above methods according to the 7 and 8th is z. B. a cleaning cloth 26 to 9 generates, which knob in a conventional manner Known 27 and which consists of either a textile fabric, knitted or woven or of a sponge body with said handle nubs 27 ,

It is important that the cleaning cloth 26 on all sides with the antimicrobial coating according to the invention 4 is provided.

The same applies to the in 10 illustrated sponge 28 , which preferably consists of a synthetic foam body whose surface on all sides with the antimicrobial coating according to the invention 4 is provided.

In 5 Although it is stated that the antimicrobial coating on the fibers 6 a yarn 5 be applied. However, the invention is not limited thereto. In another embodiment, instead, the antimicrobial coating is provided 4 on the outer surface of a yarn 5 apply. Drawing this could be done so that instead of the reference 7 in 5 where the fibrous body 7 coated, now the outer circumference of the yarn 5 with the antimicrobial coating 4 is provided. In this case, the reference number is 7 in 5 to delete and against the reference 5 to replace.

If a fabric made of yarns 14 in the dipping bath 17 or coated according to another of the illustrated methods, then the coating will 4 on the surface of the fabric, namely on the surface of the fabric 14 forming yarns 5 form.

However, the invention does not exclude that the antimicrobial coating 4 the surface of the yarn 5 interspersed and on the yarn body forming fibers 6 settles, as in 3 is shown.

Accordingly, both coating mechanisms alone and a combination of both coating mechanisms are claimed to be essential to the invention.

If the fibers 6 are microfibers with a diameter of less than 1/1000 mm is of a coating of the yarn 5 and additionally the fibers 6 go out.

Advantageously, fibers with a diameter of up to 0.2 / 1000 mm are used.

The copper-oxide particles used here have a preferred diameter of 0.1 to 0.99 / 1000 mm, so are the diameter of the fibers used 6 , Also for this reason, it is assumed that the coating 4 both on the fibers 6 as well as on the yarn 5 he follows.

LIST OF REFERENCE NUMBERS

1

textile fabric

2

weft

3

warp

4

Coating (antimicrobial)

5

yarn

6

fiber

7

fiber body

8th

Elastomeric carrier substance

9

microparticles

10

substratum

11

particle core

12

Hydratmantel

13

arrow

14

web 14 '

15

delivery roller

16

arrow

17

dip

18

guide roller

19

coating suspension

20

winding roller

21

arrow

22

drying unit

23

section of material

24

tenter

25

arrow 25 '

26

cleaning cloth

27

grip nubs

28

sponge

29

30

Pigment binder system

Table 1 Table 2 Cu content of textile fabrics (std.dev. = Standard deviation) Cu-content (Std.dev.) Sample A mg / kg mg / kg Cu ₂ O binder 248.1 ± 7.26 Cu ₂ O binder washed 10 × 139.7 ± 7.30 Sample B Cu ₂ O binder 272.3 ± 30.2 Cu ₂ O binder washed 10 × 170.1 ± 9.23 Table 2 and 3 Table 2 Reduction of the bacterial viability of Staphylococcus aureus as a function of time (blank = untreated tissue) Time 1 h 24 hours Sample A bright 0 0 Cu ₂ O 16.2 100 Cu ₂ O (10x wash) 8.2 99.6 Sample B bright 0 0 Cu ₂ O binder 10.3 84.2 Cu ₂ O (10x wash) 0 82.1 Table 3 Reduction of bacterial viability of Klebsiella pneumoniae over time (blank = untreated tissue) Time 1 h 24 hours Sample A bright 0 0 Cu ₂ O binder 28.2 92.8 Cu ₂ O binder (10 × wash) 0 78.1 Sample B bright 0 0 Cu ₂ O binder 27.4 85.3 Cu ₂ O binder (10 × wash) 0 80.5

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007003648 A1 [0006]
• DE 102007003649 A1 [0006, 0010]

Cited non-patent literature

• ASTM E2149-01 [0021]
• ASTM E2149-01 [0060]

Claims (10)

Cleaning, washing and / or polishing substrate ( 10 ) consisting of textile and / or non-woven and / or sponge-like structures for cleaning surfaces of any kind with antimicrobial properties using copper (I) oxide microparticles ( 9 ) having a particle size in the range of 1-10 microns, wherein at the surface of the substrate ( 10 ) an elastomeric coating ( 4 ) attached to an elastomeric carrier substance ( 8th ) and the copper (I) oxide particles ( 9 ) consists. Cleaning, washing and polishing substrate ( 10 ) according to claim 1, characterized in that the particle size of the copper (I) oxide microparticles ( 9 ) preferably in the range between 1.5 and 2 microns. Cleaning, washing and polishing substrate ( 10 ) according to claim 1 or 2, characterized in that the copper (I) oxide microparticles ( 9 ) from the elastomeric coating ( 4 ) are leachable by washing. Cleaning, washing and polishing substrate ( 10 ) according to at least one of claims 1 to 3, characterized in that the content of copper (I) oxide microparticles ( 9 ) in the substrate ( 10 ) is about 250 mg / kg CU before the first wash. Cleaning, washing and polishing substrate ( 10 ) according to at least one of claims 1 to 4, characterized in that the curable elastomeric coating ( 4 ) from a pigment binder system ( 30 consisting of an ABS copolymer binder and a dispersing agent into which the copper (I) oxide microparticles ( 9 ) are suspended. Cleaning, washing and polishing substrate ( 10 ) according to at least one of claims 1 to 5, characterized in that the copper (I) oxide microparticles ( 9 ) are adhered to the surface of the substrate. Process for producing a cleaning, washing and polishing substrate consisting of textile, non-woven and / or spongy substrates ( 10 ) for cleaning surfaces of any kind with antimicrobial properties using copper (I) oxide microparticles ( 9 ) having a particle size in the range of 1-10 microns, wherein at the surface of the substrate ( 10 ) an elastomeric carrier substance ( 8th ) with copper (I) oxide microparticles ( 9 ) in a liquid phase of a pigment binder system ( 30 ) are attached. A method according to claim 6, characterized in that for the preparation of the curable elastomeric coating ( 4 ) from a pigment binder system ( 30 ) a liquid ABS copolymer binder and a dispersant form a suspension into which the copper (I) oxide microparticles ( 9 ) are suspended in wet phase. Method according to one of claims 6 or 7, characterized in that the amount of use of the copper (I) oxide microparticles used ( 9 ) is about 300 ppm compared to the substrate. Method according to at least one of claims 6 to 9, characterized in that the on the surface of the substrate ( 10 ) attached elastomeric coating ( 4 ) an elastic film of the elastomeric carrier substance ( 8th ) and the copper (I) oxide particles ( 9 ), from which the copper (I) oxide particles ( 9 ) are leachable.

Images